首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7407篇
  免费   660篇
  国内免费   15篇
耳鼻咽喉   55篇
儿科学   339篇
妇产科学   230篇
基础医学   1087篇
口腔科学   156篇
临床医学   781篇
内科学   1663篇
皮肤病学   137篇
神经病学   740篇
特种医学   202篇
外国民族医学   1篇
外科学   1163篇
综合类   37篇
现状与发展   1篇
一般理论   9篇
预防医学   479篇
眼科学   162篇
药学   327篇
  1篇
中国医学   6篇
肿瘤学   506篇
  2022年   57篇
  2021年   103篇
  2020年   84篇
  2019年   103篇
  2018年   135篇
  2017年   100篇
  2016年   144篇
  2015年   126篇
  2014年   183篇
  2013年   216篇
  2012年   373篇
  2011年   385篇
  2010年   235篇
  2009年   225篇
  2008年   342篇
  2007年   398篇
  2006年   345篇
  2005年   393篇
  2004年   368篇
  2003年   377篇
  2002年   331篇
  2001年   255篇
  2000年   263篇
  1999年   228篇
  1998年   105篇
  1997年   94篇
  1996年   82篇
  1995年   97篇
  1994年   67篇
  1993年   52篇
  1992年   122篇
  1991年   122篇
  1990年   114篇
  1989年   127篇
  1988年   88篇
  1987年   87篇
  1986年   101篇
  1985年   75篇
  1984年   87篇
  1983年   62篇
  1982年   42篇
  1981年   33篇
  1980年   32篇
  1979年   69篇
  1978年   49篇
  1977年   34篇
  1976年   36篇
  1975年   38篇
  1974年   43篇
  1972年   41篇
排序方式: 共有8082条查询结果,搜索用时 11 毫秒
91.
92.
This study used a multimethod approach to evaluate the relationship of alexithymia (as measured by the 20-item Toronto Alexithymia Scale and the 30-item Emotion Awareness Questionnaire), psychosocial development (assessed with the Measure of Psychosocial Development), and risk behavior (as measured by the Youth Comprehensive Risk Assessment) in 67 adolescents (85% from rural communities) in a rural residential treatment facility. Results revealed that both measures of alexithymia demonstrated good internal consistency and convergent validity. The EAQ-30 demonstrated stronger convergent validity over the TAS-20 with psychosocial measures of shame, inferiority, and role confusion and was more robust in differentiating risk behavior among males and females. Adolescent females scored higher on measures of alexithymia than males and demonstrated significantly more shame, diminished bodily awareness, and risk to self; whereas, males demonstrated significantly more risk to others. Overall, this study contributes to the current literature of alexithymia, provides further support for the validity of the alexithymia construct with adolescents, and sheds light on the importance of emotional awareness and expression in adolescent psychosocial development. Although exploratory, this study also increases clinical understanding of how risk behavior develops and manifests differently in male and female adolescents, specifically with regard to shame and diminished bodily awareness.  相似文献   
93.
94.
The relationship of borderline infiltrates to acute rejection by Banff criteria in renal allografts of patients receiving only maintenance immunosuppression is not clear. Renal allograft biopsies with borderline lesions that were not treated with additional anti-rejection therapy were retrospectively studied. Sixty-five such biopsies were identified from 50 patients, and their outcome was determined by serum creatinine and/or histologic findings in subsequent biopsies, up to 40 d after the initial biopsy. In addition to the borderline infiltrates, there was evidence of acute cyclosporine or tacrolimus toxicity (58%), acute tubular necrosis (12%), and urinary obstruction (12%). Forty-day follow-up after 30 (46%) biopsies revealed serum creatinine < 110% of baseline, and repeat biopsies were not indicated. In 17 (26%), the serum creatinine initially decreased, then increased, and follow-up biopsies showed acute rejection in nine. In 18 (28%), the creatinine remained elevated and follow-up biopsies revealed acute rejection in nine. The untreated borderline infiltrates were thus nonprogressive after 47 biopsies (72%) and progressed to histologic acute rejection after 18 (28%). When there was increasing or persistently elevated creatinine after the initial biopsy, 51% of cases (18 of 35) progressed to acute rejection. Infiltrates that progressed to rejection had more frequent glomerulitis (7 of 18 versus 3 of 47, P = 0.003) and Banff acute score indices (i+t+v+g) >2 (16 of 18 versus 29 of 47, P = 0.03). A majority (72%) of borderline infiltrates not given additional anti-rejection therapy did not progress to acute rejection over 40 d of follow-up, suggesting that conservative management of these lesions, at least in the short term, may be more appropriate than routine treatment as acute rejection.  相似文献   
95.
BACKGROUND: We compared two repair techniques for pulmonary artery sling. The first comprised detachment of the aberrant left pulmonary artery from the right pulmonary artery and its implantation into the main pulmonary artery, and the second, translocation of the left pulmonary artery anterior to the trachea (without implanting it into the main pulmonary artery), resection of tracheal stenosis, and end-to-end reconstruction of the trachea. METHODS: Five symptomatic infants (3 boys and 2 girls; median age 5 months; range, 3 weeks to 11 months) with pulmonary artery sling were operated on through a median sternotomy with aid of cardiopulmonary bypass. In 3 patients, the left pulmonary artery was transected from the right pulmonary artery and implanted into the main pulmonary artery. In addition, the anterior trachea was augmented with a pericardial patch (n = 2). In the remaining 2 patients, associated tracheal stenosis was resected, the left pulmonary artery was translocated anterior to the trachea, and the trachea was reconstructed. RESULTS: All 5 infants survived the operation. The 3 patients in whom the left pulmonary artery was implanted into the main pulmonary artery had an uncomplicated postoperative course. All 3 patients, at a follow-up of 10 months to 7.9 years, were free of symptoms; the left pulmonary artery was documented to be widely patent. The remaining 2 patients in whom the left pulmonary artery was translocated anterior to the trachea could not be extubated. In both patients the distal trachea was compressed anteriorly by the left pulmonary artery. One of these patients died at 1 week postoperatively secondary to tracheal dehiscence. In the other patient, the left pulmonary artery was implanted into the main pulmonary artery with good result; at a follow-up of 3.9 years, mild residual stridor has persisted. CONCLUSIONS: In pulmonary artery sling, implantation of the aberrant left pulmonary artery into the main pulmonary artery, if necessary combined with anterior tracheoplasty, reliably eliminates tracheal and esophageal compression and maintains antegrade flow into the left pulmonary artery. Translocation of the left pulmonary artery anterior to the trachea without implanting it into the main pulmonary artery is not favored because that might result in anterior compression of the trachea. In addition, we are concerned about growth of the circumferential tracheal anastomosis in neonates and infants.  相似文献   
96.
OBJECTIVE: To estimate the occupational risk to dental anesthesiologists of contracting 3 bloodborne pathogens: hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency virus (HIV). METHODS: Through an anonymously returned, mailed questionnaire, dental anesthesiologists in Canada and the United States provided information regarding percutaneous and mucocutaneous contacts with contaminated fluid during the treatment of patients under deep sedation and general anesthesia as well as other general practice information. A mathematical model was applied to determine the occupational risk. RESULTS: Of the 101 (65%) returned questionnaires, 98 reported having treated patients within the previous 6 months. Of these, 41 (42%) had at least one percutaneous accident (89 accidents in total), and the projected mean annual injury rate for dental anesthesiologists overall was 1.82. The most common causes of injury were burs, intraoral needles, and dental instruments. Operator error during use was associated with 31% of reported accidents. Significantly more injuries were reported by those who also reported a mucocutaneous contact and by those working more than 25 hours per week. The projected mean annual number of mucocutaneous exposures was 0.88 for dental anesthesiologists overall. CONCLUSIONS: The calculated annual risk to the average dental anesthesiologist of acquiring HBV (if not immune), HCV, and HIV following percutaneous injury was very low for all infections (HBV the most; HIV the least). The risk of contracting HIV following mucocutaneous contact was extremely low.  相似文献   
97.
BACKGROUND: Necrotizing and crescentic glomerulonephritis related to antineutrophil cytoplasmic autoantibodies (ANCA) is typically referred to as "pauci-immune"; however, it is not unusual for renal biopsies in such cases to exhibit some immune complex deposition within glomeruli on immunofluorescence and/or electron microscopic study. The composition and intraglomerular localization of such deposits in ANCA-glomerulonephritis has not been widely studied, and their potential pathologic and clinical significance is not clear, although a possible synergistic effect between immune complexes and ANCA in producing more severe glomerulonephritis is suggested by some human and animal studies. METHODS: Electron micrographs from 126 renal biopsies showing necrotizing/crescentic glomerulonephritis characterized by positive ANCA serology [C-ANCA, anti-proteinase 3 (anti-PR3), or anti-myeloperoxidase (MPO)] or necrotizing arteritis in the absence of known ANCA results were examined for the presence, quantity, and location of electron-dense deposits. The presence or absence of such deposits was correlated with histologic findings (fraction of glomeruli with crescents and segmental necrotizing lesions, mesangial and endocapillary hypercellularity), immunofluorescence findings, and clinical data, including serum creatinine and 24-hour urine protein levels at the time of biopsy. RESULTS: Sixty-eight (54%) of these biopsies showed glomerular immune complex deposits on electron microscopy; 87% of the latter also showed positive immunofluorescence findings for at least one immunoglobulin or complement component, although staining was relatively mild in most instances (< or =2+ on a 0 to 4+ scale in all but eight cases). Nearly half of biopsies negative for deposits by electron microscopy also showed positive immunofluorescence findings, though even more so than in cases with deposits on electron microscopy the intensity of immunofluorescence staining in these biopsies was typically very weak (trace or trace to 1+ in most cases, none >2+). Hypercellularity within the glomerular tuft was seen in 50% of biopsies with deposits on electron microscopy but only 14% of those without deposits; in each group this was usually mild and mesangial. Notably, the presence of deposits on electron microscopy was associated with a higher median level of proteinuria (3.2 versus 1.3 g/24 hours, P < 0.0001) and a higher median percentage of glomeruli with crescents (62.5% versus 44.0%, P= 0.06). CONCLUSION: Immune complex deposits were found on electron microscopy in just over half of renal biopsies with crescentic glomerulonephritis associated with positive ANCA serology and/or necrotizing arteritis. Clinical correlations suggest that these immune complex deposits may somehow potentiate the effect of ANCA in producing glomerulonephritis.  相似文献   
98.
This randomized, active-controlled study evaluated the extent and duration of analgesia after administration of liposome bupivacaine (LB), a novel formulation of bupivacaine, compared with bupivacaine HCl given via local infiltration in excisional hemorrhoidectomy. One hundred patients were randomly assigned to receive a single dose of bupivacaine HCl 75 mg (0.25% with 1:200,000 epinephrine) or LB 66, 199, or 266 mg upon completion of hemorrhoidectomy. Postoperative pain intensity was assessed using a numeric rating scale at rest to calculate a cumulative pain score (area under the curve). Cumulative pain scores were significantly lower with LB at each study dose (P < 0.05) compared with bupivacaine HCl 72 hours after surgery. Post hoc analysis showed that mean total postoperative opioid consumption was statistically significantly lower for the LB 266-mg group compared with the bupivacaine HCl group during the 12- to 72-hour postoperative period (P = 0.019). Median time to first opioid use was 19 hours for LB 266 mg versus 8 hours for bupivacaine HCl (P = 0.005). Incidence of opioid-related adverse events was 4 per cent for LB 266 mg compared with 35 per cent for bupivacaine HCl (P = 0.007). Local infiltration with LB resulted in significantly reduced postsurgical pain compared with bupivacaine HCl in patients after hemorrhoidectomy surgery.  相似文献   
99.
Osteoclast formation from the hemopoietic stem cell line FDCP-mix C2GM was shown to be strongly dependent on osteoblast density. In cocultures of C2GM cells with fetal mouse osteoblasts seeded at high density (i.e., 2.5 × 104 cells/cm2), we found a significantly lower osteoclast formation compared with cocultures with osteoblasts seeded at low density (i.e., 1 × 104 cells/cm2). The differentiation state of osteoblasts in high-density cultures resembled more than that of osteoblasts in low-density cultures, the differentiation state of mature osteoblasts, since the cells in the former cultures showed higher alkaline phosphatase (APase) activity than the cells in the latter cultures, and nodules were formed in high-density cultures but not in low-density cultures. Endogenous interleukin-6 (IL-6) production was found to be significantly lower in high-density cultures, which may partly explain the impaired osteoclast formation in high-density cocultures. Addition of IL-6 to the high-density cocultures indeed restored osteoclast formation. There appeared to be no overt difference in IL-6 receptor mRNA expression between high-density and low-density cultures. In conclusion, this paper suggests that mature, highly differentiated osteoblasts are not directly involved in osteoclastogenesis. In contrast, osteoblast-like cells lacking mature osteoblast markers induce osteoclast formation. Whether these low-density osteoblast-like cells represent an immature differentiation state or the lining cell phenotype is unclear. Received: 26 June 1997 / Accepted: 14 November 1997  相似文献   
100.
The aim of this study was to assess the need and demand for sedation or general anesthesia (GA) for dentistry in the Canadian adult population. A national telephone survey of 1101 Canadians found that 9.8% were somewhat afraid of dental treatment, with another 5.5% having a high level of fear. Fear or anxiety was the reason why 7.6% had ever missed, cancelled, or avoided a dental appointment. Of those with high fear, 49.2% had avoided a dental appointment at some point because of fear or anxiety as opposed to only 5.2% from the no or low fear group. Regarding demand, 12.4% were definitely interested in sedation or GA for their dentistry and 42.3% were interested depending on cost. Of those with high fear, 31.1% were definitely interested, with 54.1% interested depending on cost. In a hypothetical situation where endodontics was required because of a severe toothache, 12.7% reported high fear. This decreased to 5.4% if sedation or GA were available. For this procedure, 20.4% were definitely interested in sedation or GA, and another 46.1% were interested depending on cost. The prevalence of, and preference for, sedation or GA was assessed for specific dental procedures. The proportion of the population with a preference for sedation or GA was 7.2% for cleaning, 18% for fillings or crowns, 54.7% for endodontics, 68.2% for periodontal surgery, and 46.5% for extraction. For each procedure, the proportion expressing a preference for sedation or GA was significantly greater than the proportion having received treatment with sedation or GA (P < 0.001). In conclusion, this study demonstrates that there is significant need and demand for sedation and GA in the Canadian adult population.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号