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   992704篇
  免费   76873篇
  国内免费   2608篇
耳鼻咽喉   12973篇
儿科学   34490篇
妇产科学   28498篇
基础医学   144688篇
口腔科学   27699篇
临床医学   89978篇
内科学   192440篇
皮肤病学   22934篇
神经病学   78787篇
特种医学   38456篇
外国民族医学   314篇
外科学   149324篇
综合类   23702篇
一般理论   386篇
预防医学   77438篇
眼科学   22571篇
药学   71802篇
  3篇
中国医学   1955篇
肿瘤学   53747篇
  2018年   10623篇
  2017年   8276篇
  2016年   9420篇
  2015年   10648篇
  2014年   14484篇
  2013年   22078篇
  2012年   29129篇
  2011年   30941篇
  2010年   18572篇
  2009年   17518篇
  2008年   28898篇
  2007年   30600篇
  2006年   31080篇
  2005年   29738篇
  2004年   29029篇
  2003年   27864篇
  2002年   26819篇
  2001年   46913篇
  2000年   47951篇
  1999年   40061篇
  1998年   10614篇
  1997年   9545篇
  1996年   9548篇
  1995年   9734篇
  1994年   9075篇
  1993年   8434篇
  1992年   32243篇
  1991年   31499篇
  1990年   31048篇
  1989年   29908篇
  1988年   27193篇
  1987年   27346篇
  1986年   25447篇
  1985年   24631篇
  1984年   18403篇
  1983年   15499篇
  1982年   9273篇
  1981年   8343篇
  1979年   16853篇
  1978年   12214篇
  1977年   10302篇
  1976年   9731篇
  1975年   10173篇
  1974年   12319篇
  1973年   11839篇
  1972年   10898篇
  1971年   10119篇
  1970年   9391篇
  1969年   8725篇
  1968年   8101篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Dumps  C.  Umrath  V.  Rupprecht  B.  Schimpf  J.  Benak  J. 《Der Anaesthesist》2022,71(1):65-82
Die Anaesthesiologie - Durch die Entwicklung von kompakten und mobileren Geräten ist der Einsatz der transösophagealen Echokardiographie (TEE) als Point-of-care-Diagnostikum in...  相似文献   
82.
Transforming growth factor-β (TGF-β) superfamily signaling via their cognate receptors is frequently modified by TGF-β superfamily co-receptors. Signaling through SMAD-mediated pathways may be enhanced or depressed depending on the specific co-receptor and cell context. This dynamic effect on signaling is further modified by the release of many of the co-receptors from the membrane to generate soluble forms that are often antagonistic to the membrane-bound receptors. The co-receptors discussed here include TβRIII (betaglycan), endoglin, BAMBI, CD109, SCUBE proteins, neuropilins, Cripto-1, MuSK, and RGMs. Dysregulation of these co-receptors can lead to altered TGF-β superfamily signaling that contributes to the pathophysiology of many cancers through regulation of growth, metastatic potential, and the tumor microenvironment. Here we describe the role of several TGF-β superfamily co-receptors on TGF-β superfamily signaling and the impact on cellular and physiological functions with a particular focus on cancer, including a discussion on recent pharmacological advances and potential clinical applications targeting these co-receptors.  相似文献   
83.
Neuroscience and Behavioral Physiology - Anxiety behavior was studied in adult pied flycatchers raising broods of chicks from early and late broods laid to replace predated clutches; its effect on...  相似文献   
84.
Childbirth rates in classical Hodgkin lymphoma (cHL) survivors have historically been reduced compared to the general population. Understanding if contemporary treatment protocols are associated with reduced fertility is crucial as treatment guidelines shift toward more liberal use of intensive chemotherapy. We identified 2834 individuals aged 18-40 years with cHL in Swedish and Danish lymphoma registers, and in the clinical database at Oslo University Hospital diagnosed 1995-2018, who were linked to national medical birth registers. Cox regression adjusted for stage, performance status, year, and age at diagnosis was used to estimate hazard ratios (HRs) and 95% confidence intervals (CI) contrasting time to first childbirth by treatment groups (ABVD, 2-4 BEACOPP, 6-8 BEACOPP) up to 10 years after diagnosis. Overall, 74.8% of patients were treated with ABVD, 3.1% with 2-4 BEACOPP and 11.2% with 6-8 BEACOPP. Adjusted HRs comparing childbirth rates in individuals treated with 6-8 BEACOPP, and 2-4 BEACOPP to ABVD were 0.53 (CI: 0.36-0.77) and 0.33 (CI: 0.12-0.91) for males, and 0.91 (CI: 0.61-1.34) and 0.38 (CI: 0.12-1.21) for females. Cumulative incidence of childbirths after 10 years was 19.8% (CI: 14.5%-27.0%) for males and 34.3% (CI: 25.8%-45.6%) for females treated with 6-8 BEACOPP. Proportions of children born after assisted reproductive technique (ART) treatments were 77.4% (CI: 60.2-88.6%) for males following 6-8 BEACOPP, and <11% for females. Among ABVD treated patients the corresponding proportions were 12.2% (CI: 8.5%-17.3%) and 10.6% (CI: 7.4%-14.9%). BEACOPP treatment is associated with decreased childbirth rates compared to ABVD in male, but not female, cHL patients, despite widespread access to ART in the Nordics.  相似文献   
85.
86.
Myocardial injury due to ischaemia within 30 days of non-cardiac surgery is prognostically relevant. We aimed to determine the discrimination, calibration, accuracy, sensitivity and specificity of single-layer and multiple-layer neural networks for myocardial injury and death within 30 postoperative days. We analysed data from 24,589 participants in the Vascular Events in Non-cardiac Surgery Patients Cohort Evaluation study. Validation was performed on a randomly selected subset of the study population. Discrimination for myocardial injury by single-layer vs. multiple-layer models generated areas (95%CI) under the receiver operating characteristic curve of: 0.70 (0.69–0.72) vs. 0.71 (0.70–0.73) with variables available before surgical referral, p < 0.001; 0.73 (0.72–0.75) vs. 0.75 (0.74–0.76) with additional variables available on admission, but before surgery, p < 0.001; and 0.76 (0.75–0.77) vs. 0.77 (0.76–0.78) with the addition of subsequent variables, p < 0.001. Discrimination for death by single-layer vs. multiple-layer models generated areas (95%CI) under the receiver operating characteristic curve of: 0.71 (0.66–0.76) vs. 0.74 (0.71–0.77) with variables available before surgical referral, p = 0.04; 0.78 (0.73–0.82) vs. 0.83 (0.79–0.86) with additional variables available on admission but before surgery, p = 0.01; and 0.87 (0.83–0.89) vs. 0.87 (0.85–0.90) with the addition of subsequent variables, p = 0.52. The accuracy of the multiple-layer model for myocardial injury and death with all variables was 70% and 89%, respectively.  相似文献   
87.
It is unclear which criteria should be used to define readiness for tracheal extubation in the operating theatre. We studied the effects of desaturation in the operating theatre immediately after tracheal extubation on long-term outcomes. Performing a pre-specified, retrospective analysis of 71,025 cases involving previously independent adults undergoing non-cardiac surgery, we evaluated the association between desaturation events (oxygen saturation < 90%) within 10 min of tracheal extubation and adverse discharge (to a skilled nursing facility or long-term care facility). A total of 404 (12.3%) cases with, and 5035 (7.4%) cases without, early postoperative desaturation had an adverse discharge. Early postoperative desaturation was associated with higher odds of being discharged to a nursing facility (adjusted odds ratio 1.36 (95%CI 1.20–1.54); p < 0.001). Increased duration of desaturation augmented the effect (p for trend < 0.001). Desaturation was associated with a higher risk of respiratory, renal and cardiovascular complications as well as increased duration of hospital stay, postoperative intensive care unit admission frequency and cost. Several modifiable factors were associated with desaturation including: high intra-operative long-acting opioid administration; high neostigmine dose; high intra-operative inspired oxygen concentration; and low oxygen delivery immediately before tracheal extubation. There was substantial provider variability between anaesthetists in the incidence of postoperative desaturation unexplained by patient- and procedure-related factors. Early postoperative desaturation is a potentially preventable complication associated with a higher risk of adverse discharge disposition. Anaesthetists may consider developing guidelines to define tracheal extubation readiness that contain postoperative desaturation as an adverse outcome after tracheal extubation.  相似文献   
88.
89.

Objectives

To investigate whether functional overreaching affects locomotor system behaviour when running at fixed relative intensities and if any effects were associated with changes in running performance.

Design

Prospective intervention study.

Methods

Ten trained male runners completed three training blocks in a fixed order. Training consisted of one week of light training (baseline), two weeks of heavy training designed to induce functional overreaching, and ten days of light taper training designed to allow athletes to recover from, and adapt to, the heavy training. Locomotor behaviour, 5-km time trial performance, and subjective reports of training status (Daily Analysis of Life Demands for Athletes (DALDA) questionnaire) were assessed at the completion of each training block. Locomotor behaviour was assessed using detrended fluctuation analysis of stride intervals during running at speeds corresponding to 65% and 85% of maximum heart rate (HRmax) at baseline.

Results

Time trial performance (effect size ±95% confidence interval (ES): 0.16 ± 0.06; p < 0.001), locomotor behaviour at 65% HRmax (ES: ?1.12 ± 0.95; p = 0.026), and DALDA (ES: 2.55 ± 0.80; p < 0.001) were all detrimentally affected by the heavy training. Time trial performance improved relative to baseline after the taper (ES: ?0.16 ± 0.10; p = 0.003) but locomotor behaviour at 65% HRmax (ES: ?1.18 ± 1.17; p = 0.048) and DALDA (ES: 0.92 ± 0.90; p = 0.045) remained impaired.

Conclusions

Locomotor behaviour during running at 65% HRmax was impaired by functional overreaching and remained impaired after a 10-day taper, despite improved running performance. Locomotor changes may increase injury risk and should be considered within athlete monitoring programs independently of performance changes.  相似文献   
90.
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