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   35920篇
  免费   3214篇
  国内免费   1310篇
耳鼻咽喉   341篇
儿科学   608篇
妇产科学   552篇
基础医学   5263篇
口腔科学   985篇
临床医学   3305篇
内科学   6500篇
皮肤病学   668篇
神经病学   2885篇
特种医学   1298篇
外国民族医学   2篇
外科学   4813篇
综合类   3314篇
一般理论   8篇
预防医学   2170篇
眼科学   823篇
药学   3502篇
  1篇
中国医学   700篇
肿瘤学   2706篇
  2023年   184篇
  2022年   232篇
  2021年   617篇
  2020年   429篇
  2019年   566篇
  2018年   836篇
  2017年   692篇
  2016年   686篇
  2015年   851篇
  2014年   1048篇
  2013年   1297篇
  2012年   1751篇
  2011年   1740篇
  2010年   1099篇
  2009年   918篇
  2008年   1471篇
  2007年   1641篇
  2006年   1485篇
  2005年   1293篇
  2004年   1100篇
  2003年   1026篇
  2002年   856篇
  2001年   2410篇
  2000年   2330篇
  1999年   1926篇
  1998年   734篇
  1997年   507篇
  1996年   357篇
  1995年   346篇
  1994年   290篇
  1993年   246篇
  1992年   1028篇
  1991年   925篇
  1990年   825篇
  1989年   913篇
  1988年   821篇
  1987年   756篇
  1986年   709篇
  1985年   614篇
  1984年   391篇
  1983年   325篇
  1982年   184篇
  1981年   143篇
  1980年   118篇
  1979年   201篇
  1973年   96篇
  1972年   93篇
  1971年   98篇
  1970年   84篇
  1968年   85篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
91.
92.
93.

Background

Patients with shoulder and rotator cuff pathology who exhibit greater levels of psychological distress report inferior preoperative self-assessments of pain and function. In several other areas of orthopaedics, higher levels of distress correlate with a higher likelihood of persistent pain and disability after recovery from surgery. To our knowledge, the relationship between psychological distress and outcomes after arthroscopic rotator cuff repair has not been similarly investigated.

Questions/purposes

(1) Are higher levels of preoperative psychological distress associated with differences in outcome scores (visual analog scale [VAS] for pain, Simple Shoulder Test, and American Shoulder and Elbow Surgeons score) 1 year after arthroscopic rotator cuff repair? (2) Are higher levels of preoperative psychological distress associated with less improvement in outcome scores (VAS for pain, Simple Shoulder Test, and American Shoulder and Elbow Surgeons score) 1 year after arthroscopic rotator cuff repair? (3) Does the prevalence of psychological distress in a population with full-thickness rotator cuff tears change when assessed preoperatively and 1 year after arthroscopic rotator cuff repair?

Methods

Eighty-five patients with full-thickness rotator cuff tears were prospectively enrolled; 70 patients (82%) were assessed at 1-year followup. During the study period, the three participating surgeons performed 269 rotator cuff repairs; in large part, the low overall rate of enrollment was related to two surgeons enrolling only two patients total in the initial 14 months of the study. Psychological distress was quantified using the Distress Risk Assessment Method questionnaire, and patients completed self-assessments including the VAS for pain, the Simple Shoulder Test, and the American Shoulder and Elbow Surgeons score preoperatively and 1 year after arthroscopic rotator cuff repair. Fifty of 85 patients (59%) had normal levels of distress, 26 of 85 (31%) had moderate levels of distress, and nine of 85 (11%) had severe levels of distress. Statistical models were used to assess the effect of psychological distress on patient self-assessment of shoulder pain and function at 1 year after surgery.

Results

With the numbers available, distressed patients were not different from nondistressed patients in terms of postoperative VAS for pain (1.9 [95% confidence interval {CI}, 1.0–2.8] versus 1.0 [95% CI, 0.5–1.4], p = 0.10), Simple Shoulder Test (9 [95% CI, 8.1–10.4] versus 11 [95% CI, 10.0–11.0], p = 0.06), or American Shoulder and Elbow Surgeons scores (80 [95% CI, 72–88] versus 88 [95% CI, 84–92], p = 0.08) 1 year after arthroscopic rotator cuff repair. With the numbers available, distressed patients also were not different from nondistressed patients in terms of the amount of improvement in scores between preoperative assessment and 1-year followup on the VAS for pain (3 [95% CI, 2.2–4.1] versus 2 [95% CI, 1.4–2.9], p = 0.10), Simple Shoulder Test (5.2 [95% CI, 3.7–6.6] versus 5.0 [95% CI, 4.2–5.8], p = 0.86), or American Shoulder and Elbow Surgeons scale (38 [95% CI, 29–47] versus 30 [95% CI, 25–36], p = 0.16). The prevalence of psychological distress in our patient population was lower at 1 year after surgery 14 of 70 (20%) versus 35 of 85 (41%) preoperatively (odds ratio, 0.36; 95% CI, 0.17–0.74; p = 0.005).

Conclusions

Mild to moderate levels of distress did not diminish patient-reported outcomes to a clinically important degree in this small series of patients with rotator cuff tears. This contrasts with reports from other areas of orthopaedic surgery and may be related to a more self-limited course of symptoms in patients with rotator cuff disease or possibly to a beneficial effect of rotator cuff repair on sleep quality or other unrecognized determinants of psychosocial status.

Level of Evidence

Level I, prognostic study.  相似文献   
94.
The aim of this study was to isolate and characterise porcine spermatogonial stem cells (PSSCs). The putative porcine germline stem cells from testis were isolated successfully by an improving way of enrichment with lymphocyte separation medium (LSM). Results from RT‐PCR analyses showed that PSSCs were positive for OCT4, SOX2, NANOG, PGP9.5, c‐MYC, KEL4 and PRDM‐14 which are multipotent stem cell markers. At the protein level, the results of immunofluorescence analyses showed that PSSCs were positive for OCT4, PGP9.5, SOX2 and CD29. We successfully differentiated these PSSCs into adipocytes and muscle cells and then defined their characteristics, including morphology, surface stem cell markers, and mechanical properties. But the experiment of teratoma formation was negative. The results indicated the PSSCs could be multipotent. Atomic force microscopy was used to characterise the morphological and mechanical properties of undifferentiated PSSCs, as well as the differentiated adipocytes and muscle cells, which could be potentially useful for distinguishing PSSCs from differentiated cells.  相似文献   
95.
J. Li  Y. Hu  Q. Zhang  B. Ma  Z. Wu  Y. Wang  J. Sun  J. Zhu  H. Ying  P. Ouyang 《Andrologia》2015,47(9):995-1003
This study investigated the treatment effects of a new compound, strontium fructose 1, 6‐diphosphate (FDP‐Sr), in cyclophosphamide (CP)‐induced oligozoospermia. FDP‐Sr, with extra high‐energy supply, could reverse male hypogonadism in the testis. Male Wistar rats were randomly divided into three groups: control group (vehicle treated), CP group and CP + FDP‐Sr group. Both CP group and CP + FDP‐Sr groups were orally administered CP (20 mg kg?1) consecutively for the first 7 days to establish CP‐induced testicular toxic models. Subsequently, CP group was given orally distilled water per day, whereas CP + FDP‐Sr group was received FDP‐Sr (200 mg kg?1) for 49 days. Compared to the CP group, the FDP‐Sr group showed significantly increased levels of serum testosterone, testis relative weights and epididymal sperm counts in rats. In addition, rats treated by FDP‐Sr showed the recuperative activities of testicular marker enzymes and normalised levels of antioxidants in tissue. Testicular protection of FDP‐Sr was further demonstrated by enhancing expression of P450scc, reducing ability of FAS/FASL and generating cytoprotection in the histopathological study. FDP‐Sr appeared to possess an ability to attenuate CP‐induced reproduction toxicity via the activation of antioxidants and steroidogenesis enzymes, and alleviate oligozoospermia via inhibition of testicular apoptosis by FAS/FASL pathway.  相似文献   
96.
Unloading, neural lesions, and hormonal disorders after acute motor‐complete spinal cord injury (SCI) cause one of the most severe forms of bone loss, a condition that has been refractory to available interventions tested to date. Thus, these features related to acute SCI provide a unique opportunity to study complex bone problems, potential efficacious interventions, and mechanisms of action that are associated with these dramatic pathological changes. This study was designed to explore the therapeutic potential of sclerostin antibody (Scl‐Ab) in a rat model of bone loss after motor‐complete SCI, and to investigate mechanisms underlying bone loss and Scl‐Ab action. SCI rats were administered Scl‐Ab (25 mg/kg/week) or vehicle beginning 7 days after injury then weekly for 7 weeks. SCI resulted in significant decreases in bone mineral density (–25%) and trabecular bone volume (–67%) at the distal femur; Scl‐Ab completely prevented these deteriorations of bone in SCI rats, concurrent with markedly increased bone formation. Scanning electron microscopy revealed that SCI reduced numbers of osteocytes and dendrites concomitant with a morphology change from a spindle to round shape; Scl‐Ab corrected these abnormalities in osteocytes. In ex vivo cultures of bone marrow cells, Scl‐Ab inhibited osteoclastogenesis, and promoted osteoblastogenesis accompanied by increases in mRNA levels of LRP5, osteoprotegerin (OPG), and the OPG/RANKL ratio, and a decrease in DKK1 mRNA. Our findings provide the first evidence that robust bone loss after acute motor‐complete SCI can be blocked by Scl‐Ab, at least in part, through the preservation of osteocyte morphology and structure and related bone remodeling. Our findings support the inhibition of sclerostin as a promising approach to mitigate the striking bone loss that ensues after acute motor‐complete SCI, and perhaps other conditions associated with disuse osteoporosis as a consequence of neurological disorders. © 2015 American Society for Bone and Mineral Research  相似文献   
97.
There were controversial results between obesity‐associated markers and semen quality. In this study, we investigated the correlations between age, obesity‐associated markers including body mass index (BMI), waist‐to‐hip ratio (WHR), waist‐to‐height ratio (WHtR) and waist circumference (WC), the combination of age and obesity‐associated markers, semen parameters and serum reproductive hormone levels in 1231 subfertile men. The results showed that BMI, WC, WHR and WHtR were positively related to age, and there were also positive relations between BMI, WHR, WC and WHtR and between sperm concentration (SC), total sperm count (TSC), progressive motility (PR), sperm motility and per cent of normal sperm morphology (NSM). However, age, each of obesity‐associated markers and the combination of obesity‐associated markers and age were unrelated to any of semen parameters including total normal‐progressively motile sperm count (TNPMS). Age, BMI, WHR, WC and WHtR were negatively related to serum testosterone and SHBG levels. However, only serum LH and FSH levels were negatively related to sperm concentration, NSM and sperm motility. In a conclusion, although age and obesity have significant impacts on reproductive hormones such as testosterone, SHBG and oestradiol, semen parameters related to FSH and LH could not be influenced, indicating that obesity‐associated markers could not predict male semen quality.  相似文献   
98.
99.
100.
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