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   14948篇
  免费   932篇
  国内免费   94篇
耳鼻咽喉   131篇
儿科学   320篇
妇产科学   878篇
基础医学   1907篇
口腔科学   313篇
临床医学   1681篇
内科学   3152篇
皮肤病学   276篇
神经病学   1141篇
特种医学   424篇
外科学   1993篇
综合类   281篇
一般理论   8篇
预防医学   792篇
眼科学   426篇
药学   1069篇
中国医学   127篇
肿瘤学   1055篇
  2023年   67篇
  2022年   199篇
  2021年   358篇
  2020年   154篇
  2019年   310篇
  2018年   417篇
  2017年   250篇
  2016年   281篇
  2015年   441篇
  2014年   536篇
  2013年   750篇
  2012年   1106篇
  2011年   1177篇
  2010年   746篇
  2009年   602篇
  2008年   871篇
  2007年   866篇
  2006年   829篇
  2005年   797篇
  2004年   727篇
  2003年   637篇
  2002年   612篇
  2001年   549篇
  2000年   526篇
  1999年   376篇
  1998年   108篇
  1997年   100篇
  1996年   91篇
  1995年   78篇
  1994年   66篇
  1993年   56篇
  1992年   182篇
  1991年   152篇
  1990年   117篇
  1989年   112篇
  1988年   105篇
  1987年   82篇
  1986年   71篇
  1985年   62篇
  1984年   46篇
  1983年   32篇
  1982年   25篇
  1981年   23篇
  1980年   18篇
  1979年   42篇
  1978年   24篇
  1977年   22篇
  1976年   20篇
  1975年   24篇
  1973年   25篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We conducted a retrospective, 7 year cohort survey to examine the natural changes in peritoneal equilibration test (PET) results in patients with long-term uneventful continuous ambulatory peritoneal dialysis (CAPD). Thirty-two (17 males, 15 females) patients on CAPD with two or more standard PETs performed more than 6 months apart, in the absence of peritoneal insult, were included. Changes and pattern of PET results were evaluated by the dialysate to plasma ratio of creatinine (D:P-cre), the fourth h dialysate to instilled glucose ratio (D4:Do) and ultrafiltration volume (UF, ml). The subgroups included high (H), high-average (HA), low-average (LA), or low (L) transporters with the dividing ratios (D:P-cre) of >0.81, >0. 65 to 0.81, >0.5 to 0.65, and <0.5, respectively. The median D:P-cre significantly decreased (p = 0.04), but neither the D4:Do nor the final median UF significantly decreased. The change in D:P-cre was strongly and inversely correlated with the initial D:P-cre value (r = -0.68; p < 0.05). A similar relationship was found between the change in the final D4:Do and the initial D4:Do (r = -0.752; p < 0. 01) and between the change in the final UF and the initial UF (r = -0.875; p < 0.01). No correlation was found between the change in D:P-cre and the age of the patient, the time interval between PETs, monthly dialysate glucose exposure, or underlying diabetes/non-diabetes. The final peritoneal transport pattern was altered with 5 (15.6%) patients remaining in the extreme subgroups (H or L) and, by contrast, 84.4% (27/32) of the patients now in the averaged (HA or LA) groups (p < 0.01, chi2 test). We demonstrated a natural "centralization" migration of PET results after long-term uneventful CAPD, which may help to explain why patients with extreme PET characteristics, that is, H or L, continued to do well on CAPD.  相似文献   
82.
83.
84.
Objective: To compare the pregnancy rates, between intrauterine insemination (IUI) followed by timed intercourse and IUI only for treatment of the infertile couples. Study design: A prospective study of two different protocols of intrauterine insemination in two hundred and one infertile couples with a normal spermiogram was carried out. Of these, 101 couples were treated with IUI alone and 100 couples had both IUI and timed intercourse within a 12-18 h period. The pregnancy rates were compared between groups. Results: The characteristics of the two groups were similar in terms of the mean age, as well as the duration and causes of infertility. The cycle characteristics following follicular stimulation were also similar between two groups. The pregnancy rate per cycle increased with increasing numbers of total motile sperm per insemination in the IUI alone group (P=0.045). Timed intercourse increased pregnancy rate in patients with lower motile sperm number (<40×106) (27.7% versus 10.5%, P=0.023), but not in patients with higher sperm number (≥40×106) (25.7% versus 22.7%, P=0.671). Conclusions: In IUI with low number of motile sperm inseminated, timed intercourse significantly increases the pregnancy rates over IUI alone in infertile couples with a normal sperminogram. This alternative treatment appears to be a practical, simple, and inexpensive addition that improves the pregnancy rate in patients receiving ovulation induction and intrauterine insemination program.  相似文献   
85.
We present a report on a case of conjoined twin/s (cephalothoracopagus janiceps monosymmetros) diagnosed by ultrasonography and X-ray at 27 weeks' gestation. Accepted: 29 December 1997  相似文献   
86.
Colon transit study is currently performed by delivering technetium-99m or indium-111 labelled activated charcoal to the colon in a methacrylate-coated capsule (coated capsule). However, the coating procedure is complicated and methacrylate has not been approved by the Food and Drug Administration. Therefore, a simpler method is needed for the clinical routine use of colon transit study. In this study, we used a commercial empty enteric capsule and a coated capsule for the measurement of colon transit time. We compared the in vitro stability and in vivo scintigraphy of 99mTc-labelled activated charcoal in the coated capsule and the enteric capsule to evaluate the possibility of clinical usage of the enteric capsule for colon transit time study. Activated charcoal powder was mixed with 49mTc-diethylene triamine pentaacetic acid (DTPA) and vaporized to dryness. The dry 99mTc-DTPA activated charcoal was loaded into the coated capsule and the enteric capsule. In vitro stability study was performed by immersing these capsules in a colourless buffer of variable pH which mimicked the conditions in the stomach and the small bowel. Capsule disruption was determined. Colon transit scintigraphy with 99mTc-DTPA charcoal was performed in five normal volunteers using these two capsules. The in vitro stability of these two types of capsule was similar and the colon transit scintigraphy findings were almost identical. Most capsules dissolved in the ascending colon and very few in the terminal ileum. It is concluded that enteric capsule is a suitable alternative to coated capsule for measurement of colon transit.  相似文献   
87.
IMPLICATIONS: Intraoperative transesophageal echocardiography can be useful to diagnose pulmonary venous anastomotic stenoses during lung transplantation.  相似文献   
88.
PURPOSE: We describe the establishment and preliminary characterization of a cell line designated SCRC-1, which was derived from a primary renal small cell carcinoma. MATERIALS AND METHODS: Continuous cultures of a primary stage IVa renal small cell carcinoma and a xenograft in nude mice derived therefrom were characterized by immunohistology, electron microscopy, immunofluorescence/flow cytometry, cytogenetic analysis, and an in vitro drug resistance assay. RESULTS: SCRC-1 cells were reactive with antibodies to NSE, chromogranin-A, bombesin, Bcl-2, CD44s, CD44v6, CD44v7 to 8, vimentin and S100 protein (predominantly beta-subunit), and were unreactive with antibodies to EMA, CD54, EGFR(R1), URO-5, URO-7, URO-8 and URO-10. A similar immunoprofile was also found in both the primary tumor and the xenograft. Cytogenetic analysis revealed the following common clonal aberrations in all 50 metaphases analyzed: 45, XX, t (X;10;18) (p11;p11;q11), -der(18)t(X;10;18), indicating the clonal nature of this neoplasm. SCRC-1 cells showed low drug resistance to cyclophosphamide, doxorubicin, gemcitabine and fluorouracil, intermediate resistance to carmustine and mitomycin-C, and extreme resistance to cisplatin. CONCLUSION: We have documented the initial characterization of SCRC-1, which may be the first cell line reported to be derived from a primary small cell carcinoma of the kidney. This cell line can be used for further studies uncovering the biology and histogenesis of this rare cancer and delineating differences among small cell carcinomas of the kidney and other histological types.  相似文献   
89.
BACKGROUND AND PURPOSE: Although chronic inflammatory bowel disease (IBD) is rare in Asian children, increasing numbers of pediatric patients with chronic IBD worldwide have been noted in recent years. This study was conducted to delineate the trend in incidence and clinical patterns of childhood IBD in Taiwan. METHODS: All children admitted to National Taiwan University Hospital (NTUH) between 1979 and 2000 who met the criteria for IBD, Crohn's disease (CD), ulcerative colitis (UC), probable CD (PCD), or indeterminate colitis were included. The clinical features and outcomes were analyzed retrospectively. Incidence was calculated using cases of chronic diarrhea during the same period of time as the risk population. RESULTS: IBD was diagnosed in 17 children (9 females and 8 males, aged 2 months to 18 years) during the study period. Six (35%) of these children had UC, 9 (53%) had CD, and 2 (12%) had PCD. The cumulative incidence of CD during 1979-1995 was 0.85%, and increased to 2.6% during 1996-2000 (p < 0.001), while the incidence of UC did not change significantly between these periods (from 0.85% to 0.99%, p = 0.16). The median interval from onset to diagnosis was 7.7 months. Eighty percent of patients had moderate to severe disease activity at diagnosis. The follow-up duration ranged from less than 1 year to 20 years, with a mean of 4.3 years. Two patients were lost to follow-up. Eighty six percent of patients responded to treatment, and 80% of patients had inactive to mild disease activity when re-evaluated at the end of 2000. CONCLUSION: There has been a marked recent increase in the incidence of childhood CD in Taiwan but the rate of childhood UC has remained unchanged. Eighty percent of cases of childhood IBD responded well to treatment.  相似文献   
90.
Overweight and obesity-related metabolic disorders in hospital employees.   总被引:1,自引:0,他引:1  
BACKGROUND: Obesity is associated with metabolic disorders and cardiovascular diseases. This study investigated the relationship between overweight and obese status and the incidence of type 2 diabetes, hypertension, hyperlipidemia and hyperuricemia. METHODS: This prospective cohort study comprised 1749 hospital employees who received baseline health check-ups in 1993. Data from the 1027 participants (832 women, 195 men; mean age, 36 +/- 7 years) who repeated check-ups in 2003 were used in the analysis. Relative risks (RRs) for development of metabolic disorders during follow-up associated with different body mass index (BMI) categories at baseline as defined by Asia-Pacific recommendations and the Department of Health in Taiwan were calculated after adjustment for covariates. RESULTS: The prevalence of overweight and obesity at baseline check-up were 17.6% and 14.5%, respectively. Obese subjects with baseline BMI >or= 25 kg/m2 had a significant multivariate-adjusted RR of 2.7 for hypertension, 14.8 for type 2 diabetes, 3.2 for hypertriglyceridemia, and 2.8 for hyperuricemia, compared to subjects with baseline BMI < 23.0 kg/m2. RR for diabetes was higher in women than in men, but RR for hypertriglyceridemia was higher in men. The risks of hypertension and hyperuricemia significantly increased for subjects with baseline BMI >or= 23 kg/m2, while RRs for type 2 diabetes increased significantly for baseline BMI >or= 24 kg/m2 and hypertriglyceridemia increased for baseline BMI >or= 25 kg/m2. The risks attributable to obesity (baseline BMI >or= 25 kg/m2) were 23.0% for hypertension, 70.8% for diabetes, 27.9% for hypertriglyceridemia, and 24.1% for hyperuricemia. CONCLUSION: This study revealed that a high prevalence of overweight and obesity was associated with significantly increased risk of development of type 2 diabetes, hypertension, hypertriglyceridemia and hyperuricemia in hospital employees, suggesting the need for programs to improve weight management.  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