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   36562篇
  免费   3584篇
  国内免费   39篇
耳鼻咽喉   510篇
儿科学   1021篇
妇产科学   1025篇
基础医学   5602篇
口腔科学   838篇
临床医学   4894篇
内科学   6708篇
皮肤病学   476篇
神经病学   2935篇
特种医学   1194篇
外国民族医学   1篇
外科学   4837篇
综合类   715篇
一般理论   23篇
预防医学   3761篇
眼科学   545篇
药学   2919篇
  1篇
中国医学   50篇
肿瘤学   2130篇
  2022年   257篇
  2021年   515篇
  2020年   363篇
  2019年   594篇
  2018年   656篇
  2017年   471篇
  2016年   564篇
  2015年   610篇
  2014年   809篇
  2013年   1283篇
  2012年   1698篇
  2011年   1714篇
  2010年   991篇
  2009年   878篇
  2008年   1513篇
  2007年   1553篇
  2006年   1534篇
  2005年   1512篇
  2004年   1446篇
  2003年   1390篇
  2002年   1401篇
  2001年   1264篇
  2000年   1279篇
  1999年   1103篇
  1998年   486篇
  1997年   407篇
  1996年   344篇
  1995年   376篇
  1994年   358篇
  1993年   320篇
  1992年   875篇
  1991年   828篇
  1990年   825篇
  1989年   752篇
  1988年   687篇
  1987年   703篇
  1986年   689篇
  1985年   713篇
  1984年   564篇
  1983年   473篇
  1982年   332篇
  1981年   283篇
  1980年   290篇
  1979年   467篇
  1978年   352篇
  1977年   278篇
  1976年   301篇
  1974年   306篇
  1973年   266篇
  1972年   267篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.

Objective

Although endovascular repair of abdominal aortic aneurysms (AAAs) has been demonstrated to have favorable outcomes, not all cohorts of patients with AAA fare equally well. Our goal was to investigate perioperative and 1-year outcomes in patients with end-stage renal disease (ESRD) on dialysis, who have traditionally fared worse after vascular interventions, to assess how ESRD affects outcomes in a large modern cohort of endovascular aneurysm repair (EVAR) patients.

Methods

The Vascular Quality Initiative database was queried for all patients undergoing EVAR from 2010 to 2017. ESRD patients were compared with patients not on dialysis. Propensity-matched scoring and multivariable analysis were used to isolate the effects of ESRD.

Results

Of 28,683 EVARs identified, there were 321 (1.12%) patients with ESRD on dialysis. Patients with ESRD had no difference in presenting AAA size (57.5 ± 12.7 mm vs 56.7 ± 17.2 mm; P = .44); however, they had more urgent/emergent repairs (20.6% vs 13.6%; P = .002) than those without ESRD. ESRD patients were more often younger, nonwhite, and nonobese and less likely to have commercial insurance (P < .05). ESRD patients more often had hypertension, coronary artery disease, congestive heart failure, previous lower extremity bypass, aneurysm repair, and carotid interventions (P < .05). There was no difference in the rate of concomitant procedures. Matching based on demographics, comorbidities, and operative details showed that ESRD patients had longer hospital length of stay (4.8 ± 9.4 days vs 4.1 ± 12.6 days; P = .026) and higher 30-day mortality (7% vs 2.4%; P < .001). There was no difference in cardiac, pulmonary, lower extremity, bowel, and stroke complications or return to the operating room. On multivariable analysis, ESRD was associated with 30-day mortality (odds ratio, 4.1; 95% confidence interval, 2.6-6.7; P < .001). Of the 24,750 elective EVARs, 1.04% had ESRD on dialysis. Matched data for elective EVAR show increased postoperative length of stay, hospital mortality, and 30-day mortality for ESRD patients on dialysis compared with those who are not. There was no association with postoperative myocardial infarction or pulmonary complications. At 1 year, patients with ESRD on dialysis had worse survival (78% vs 94%; P < .001), and ESRD was associated with higher mortality (hazard ratio, 3.3; 95% confidence interval, 2.5-4.2; P < .001).

Conclusions

Among patients undergoing EVAR, ESRD is independently associated with higher perioperative and 1-year mortality despite not being associated with higher postoperative complications. This should be taken into account during informed consent for EVAR and risk-benefit considerations in this high-risk population, particularly for elective repair.  相似文献   
2.

Background

The International Agency for Research on Cancer (IARC) has recently classified glyphosate as a Group 2A ‘probably carcinogenic to humans’. Due to this carcinogenic classification and resulting international debate, there is an increased demand for studies evaluating human health effects from glyphosate exposures. There is currently limited information on human exposures to glyphosate and a paucity of data regarding glyphosate's biological half-life in humans.

Objective

This study aims to estimate the human half-life of glyphosate from human urine samples collected from amenity horticulture workers using glyphosate based pesticide products.

Methods

Full void urine spot samples were collected over a period of approximately 24?h for eight work tasks involving seven workers. The elimination time and estimation of the half-life of glyphosate using three different measurement metrics: the unadjusted glyphosate concentrations, creatinine corrected concentrations and by using Urinary Excretion Rates (UER) (μg L?1, μmol/mol creatinine and UER μg L?1) was calculated by summary and linear interpolation using regression analysis.

Results

This study estimates the human biological half-life of glyphosate as approximately 5 ½, 10 and 7 ¼ hours for unadjusted samples, creatinine corrected concentrations and by using UER (μg L?1, μmol/mol creatinine, UER μg L?1), respectively. The approximated glyphosate half-life calculations seem to have less variability when using the UER compared to the other measuring metrics.

Conclusion

This study provides new information on the elimination rate of glyphosate and an approximate biological half-life range for humans. This information can help optimise the design of sampling strategies, as well as assisting in the interpretation of results for human biomonitoring studies involving this active ingredient. The data could also contribute to the development or refinement of Physiologically Based PharmacoKinetic (PBPK) models for glyphosate.  相似文献   
3.
4.

Background

There is continued debate regarding retention versus sacrificing of the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA). We sought to determine if there was a difference in range of motion (ROM) after TKA between patients with PCL sacrifice versus PCL retention when using a highly congruent polyethylene insert.

Methods

We conducted an Institutional Review Board approved retrospective study of consecutive patients receiving TKA using the same implant with a highly congruent polyethylene component implanted by one surgeon from November 2013 to January 2016. Patients were placed in 2 groups based on whether the PCL was intact or released at the time of surgery. Patient charts were reviewed for age, body mass index, PCL status at surgery (incompetent, kept intact, or released), and preoperative/postoperative knee ROM.

Results

Both groups were similar in average age (60.5 vs 60.6, respectively) and body mass index (33.3 vs 32.6, respectively). Postoperative tibial slope (5.5° PCL release, 6.6° PCL retained, P = .028) was the only alignment variable reaching significance; all other alignment and motion variables were similar.

Conclusion

Results indicate that the PCL can be successfully retained with the use of a congruent bearing design, with no evident limitation in postoperative ROM or loss of stability due to the bearing in comparison to patients who undergo PCL release.  相似文献   
5.
6.
7.
The current study assessed the success of masking omega-3 (Ω3) and psychotherapy in clinical trials of youth with depression or bipolar spectrum disorder. Participants were youth ages 7–14 with DSM-IV-TR diagnosed depressive (n = 72) or bipolar spectrum (n = 23) disorders. Inclusion diagnoses were depressive disorder, cyclothymic disorder, or bipolar disorder not otherwise specified. Exclusion diagnoses included bipolar I or II disorder, chronic medical condition or autism. Youth participated in 2 × 2 randomized controlled trials, in which they received Ω3 or placebo (PBO) and psychoeducational psychotherapy (PEP) or active monitoring (AM). Participants and study staff (including independent interviewers) were masked to Ω3/PBO allocation. Besides the masked independent interviewers, one coprincipal investigator (Co-PI) was fully masked to both conditions and completed all consensus conference ratings postrandomization. At the endpoint assessment or last completed interview, interviewers and the masked Co-PI guessed whether each child was assigned to Ω3 or PBO and to PEP or AM. Masking failure was calculated using the degree of correct guesses above chance level using binomial tests across all participants for Ω3 versus PBO and PEP versus AM. For all guessers, Ω3 allocation was guessed correctly approximately half the time (50%–52.5%). Rates of correct guessing were higher for PEP, but only the interviewer guesses were correct significantly more often (58.5%–68.7%) than chance. Reporting of masking success should be an essential element of RCTs. Psychotherapy is generally more difficult to mask, but with attentive masking procedures reasonable masking can be achieved.  相似文献   
8.
9.
The focus on recovery, not just symptom reduction, in mental health care brings a need for psychometrically sound measures of recovery. This study examined the factor structure and sensitivity to change of a common measure of mental health recovery, the Recovery Assessment Scale (RAS). We conducted a secondary data analysis from a randomized clinical trial of self-management for depression (n = 302). We tested both bifactor and the previously found five-factor model. Sensitivity to change was examined three ways: (1) between the intervention and control group; (2) across time in the intervention group; and (3) in those whose depression remitted. The previous five-factor model was supported. One subscale, no domination by symptoms, was particularly sensitive to change and showed sensitivity to change whereas the subscale reliance on others did not show change in any of the comparisons. Results suggest that the subscales of the RAS should be examined separately in future studies of recovery.  相似文献   
10.
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