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   3296篇
  免费   143篇
  国内免费   34篇
耳鼻咽喉   46篇
儿科学   69篇
妇产科学   95篇
基础医学   549篇
口腔科学   93篇
临床医学   245篇
内科学   702篇
皮肤病学   45篇
神经病学   263篇
特种医学   132篇
外科学   493篇
综合类   10篇
预防医学   141篇
眼科学   85篇
药学   368篇
中国医学   9篇
肿瘤学   128篇
  2022年   25篇
  2021年   27篇
  2020年   23篇
  2019年   24篇
  2018年   32篇
  2017年   30篇
  2016年   35篇
  2015年   56篇
  2014年   76篇
  2013年   89篇
  2012年   125篇
  2011年   144篇
  2010年   102篇
  2009年   108篇
  2008年   188篇
  2007年   204篇
  2006年   186篇
  2005年   215篇
  2004年   238篇
  2003年   223篇
  2002年   203篇
  2001年   56篇
  2000年   54篇
  1999年   57篇
  1998年   56篇
  1997年   35篇
  1996年   38篇
  1995年   39篇
  1994年   50篇
  1993年   46篇
  1992年   33篇
  1991年   31篇
  1990年   27篇
  1989年   29篇
  1988年   30篇
  1987年   29篇
  1986年   17篇
  1985年   18篇
  1984年   23篇
  1983年   26篇
  1982年   25篇
  1981年   27篇
  1980年   31篇
  1979年   13篇
  1978年   17篇
  1977年   19篇
  1976年   12篇
  1975年   25篇
  1961年   17篇
  1954年   12篇
排序方式: 共有3473条查询结果,搜索用时 14 毫秒
91.
92.
Introduction: In this study, we evaluated the role of the Netrin‐1 receptor UNC5b (Uncoordinated), a neuronal guidance molecule, during peripheral nerve regeneration using the mouse median nerve model. Materials and methods: Using Western blot analysis, we examined the expression changes of UNC5b after transection and microsurgical repair of the mouse median nerve distal to the transection site. We evaluated the histomorphometrical changes and functional recovery of the grasping force after median nerve transection and repair in wild‐type (WT) mice and UNC5b+/? heterozygous mice. Results: In Western blot analysis, we could show a high increase of UNC5b in the nerve segment distal to the injury site at day 14. Histomorphometrical analysis did not show any significant differences between WT animals and heterozygous animals. Using the functional grasping test, we could demonstrate that peripheral nerve regeneration is significantly diminished in heterozygous UNC5b+/? mice. Conclusion: By using the mouse median nerve model in transgenic animals, we demonstrate that the Netrin‐1 receptor UNC5b plays an important role during peripheral nerve regeneration. © 2012 Wiley Periodicals, Inc. Microsurgery, 2013.  相似文献   
93.
Recurrent hepatitis C virus (HCV) infection occurs universally and is regarded as a major cause of mortality after liver transplantation (LT) for HCV‐related end‐stage liver disease. We conducted this large, single‐center, retrospective study to ascertain the long‐term impact of virological response to treatment of recurrent hepatitis C on survival of LT recipients. From August 1987 to October 2011, 285 patients have received interferon‐based antiviral therapy for recurrent hepatitis C. Of these 285, 245 patients were enrolled in this study. One hundred and twenty‐six patients (51.4%) achieved sustained virological response (SVR). Relapsers (undetectable HCV‐RNA at end of treatment, becoming positive afterward) comprised 9.0% (22/245), and nonresponse (NR; never achieving undetectable HCV‐RNA) 39.6% (97/245). The median follow‐up after completion of antiviral treatment was 2081 days. Using Kaplan–Meier method, patients who achieved SVR were shown to have significantly better 5‐year patient survival (95.2%) than the NR group (49.9%) (P < 0.001), and a trend toward better 5‐year survival than relapsers (87.5%) (P = 0.14); relapsers had a significantly longer survival than NR group (P = 0.005). When compared with NR, SVR and relapse appeared to be significant predictors of better survival, independent of underlying characteristics. In conclusion, virological response, especially SVR, translates into markedly improved long‐term patient outcomes in patients transplanted for hepatitis C.  相似文献   
94.
Aims

We aimed to analyze prevalence and predictors of NOAC off-label under-dosing in AF patients before and after the index stroke.

Methods

The post hoc analysis included 1080 patients of the investigator-initiated, multicenter prospective Berlin Atrial Fibrillation Registry, designed to analyze medical stroke prevention in AF patients after acute ischemic stroke.

Results

At stroke onset, an off-label daily dose was prescribed in 61 (25.5%) of 239 NOAC patients with known AF and CHA2DS2-VASc score ≥ 1, of which 52 (21.8%) patients were under-dosed. Under-dosing was associated with age ≥ 80 years in patients on rivaroxaban [OR 2.90, 95% CI 1.05–7.9, P = 0.04; n = 29] or apixaban [OR 3.24, 95% CI 1.04–10.1, P = 0.04; n = 22]. At hospital discharge after the index stroke, NOAC off-label dose on admission was continued in 30 (49.2%) of 61 patients. Overall, 79 (13.7%) of 708 patients prescribed a NOAC at hospital discharge received an off-label dose, of whom 75 (10.6%) patients were under-dosed. Rivaroxaban under-dosing at discharge was associated with age ≥ 80 years [OR 3.49, 95% CI 1.24–9.84, P = 0.02; n = 19]; apixaban under-dosing with body weight ≤ 60 kg [OR 0.06, 95% CI 0.01–0.47, P < 0.01; n = 56], CHA2DS2-VASc score [OR per point 1.47, 95% CI 1.08–2.00, P = 0.01], and HAS-BLED score [OR per point 1.91, 95% CI 1.28–2.84, P < 0.01].

Conclusion

At stroke onset, off-label dosing was present in one out of four, and under-dosing in one out of five NOAC patients. Under-dosing of rivaroxaban or apixaban was related to old age. In-hospital treatment after stroke reduced off-label NOAC dosing, but one out of ten NOAC patients was under-dosed at discharge.

Clinical trial registration

NCT02306824.

  相似文献   
95.

Purpose

To collect data on primary treatment decision and follow-up in patients with diagnosed, histologically confirmed localized (T1a–T2c/N0/M0) prostate cancer (PCa) for up to 5 years in a prospective observational non-interventional study.

Methods

Patients were non-randomly allocated to one of the five treatment strategies: hormone therapy, active surveillance, radiation, operation, or watchful waiting.

Results

A total of 3169 patients were included by 259 participating sites; 2957 patients had at least one follow-up visit. 54.8 % of tumors at baseline were staged as T1c, 38 % as T2a–T2c, and 7.1 % as T1a or T1b (missing: 0.2 %). 38.9, 32.6 and 26.6 % of patients were classified as low risk, intermediate risk, and high risk according to d’Amico, respectively (missing: 1.8 %). 56.6 % of patients underwent prostatectomy as primary therapy, 16.4 % received radiation, 6.9 % HT, 15.8 and 4.3 % decided for AS or WW. Mean follow-up was 28.4 months. Progression rates were between 8.6 % (RT) and 33.1 % (AS).

Conclusion

Whereas RP remains the main treatment option of localized PCa, active surveillance appears to become an accepted and selectively employed treatment option. Careful selection of patients is documented by the highest proportion of patients with low risk (82.5 %), PSA density <0.2 ng/ml/ml (77.5 %), T1 staging (83.6 %), Gleason score ≤6 (92.5 %), ≤2 positive biopsies (79.4 %), and lowest mean PSA (5.8 ng/ml) in the AS group. The relatively high progression rate in the AS group has to be considered in the context of treatment changes; 71/155 patients had a documented change of treatment and 62 of them with a follow-up period of >3 months.
  相似文献   
96.
97.
98.
The cannabinoid CB1 receptors on the noradrenergic neurons in guinea pig hippocampal slices show an endogenous endocannabinoid tone. This conclusion is based on rimonabant, the facilitatory effect of which on noradrenaline release might be due to its inverse CB1 receptor agonism and/or the interruption of a tonic inhibition elicited by endocannabinoids. To examine the latter mechanism, a neutral antagonist would be suitable. Therefore, we studied whether O-2050 is a neutral CB1 receptor antagonist in the guinea pig hippocampus and whether it mimics the facilitatory effect of rimonabant. CB1 receptor affinity of O-2050 was quantified in cerebrocortical membranes, using 3H-rimonabant binding. Its CB1 receptor potency and effect on 3H-noradrenaline release were determined in superfused hippocampal slices. Its intrinsic activity at CB1 receptors was studied in hippocampal membranes, using 35S-GTPγS binding. Endocannabinoid levels in hippocampus were determined by liquid chromatography-multiple reaction monitoring. O-2050 was about ten times less potent than rimonabant in its CB1 receptor affinity, potency and facilitatory effect on noradrenaline release. Although not affecting 35S-GTPγS binding by itself, O-2050 shifted the concentration-response curve of a CB1 receptor agonist to the right but that of rimonabant to the left. Levels of anandamide and 2-arachidonoyl glycerol in guinea pig hippocampus closely resembled those in mouse hippocampus. In conclusion, our results with O-2050 confirm that the CB1 receptors on noradrenergic neurons of the guinea pig hippocampus show an endogenous tone. To differentiate between the two mechanisms leading to an endogenous tone, O-2050 is not superior to rimonabant since O-2050 may increase the inverse agonistic effect of endocannabinoids.  相似文献   
99.
CaTiO3 is a promising candidate as a pseudo-piezoelectric scaffold material for bone implantation. In this study, pure and magnesium/iron doped CaTiO3 are synthesized by sol-gel method and spark plasma sintering. Energy dispersive X-ray mapping confirm the homogenous distribution of doping elements in sintered samples. High-energy X-ray diffraction investigations reveal that doping of nanostructured CaTiO3 increased the strain and defects in the structure of CaTiO3 compared to the pure one. This led to a stronger pseudo-piezoelectric effect in the doped samples. The charge produced in magnesium doped CaTiO3 due to the direct piezoelectric effect is (2.9 ± 0.1) pC which was larger than the one produced in pure CaTiO3 (2.1 ± 0.3) pC, whereas the maximum charge was generated by iron doped CaTiO3 with (3.6 ± 0.2) pC. Therefore, the pseudo-piezoelectric behavior can be tuned by doping. This tuning of pseudo-piezoelectric response provides the possibility to systematically study the bone response using different piezoelectric strengths and possibly adjust for bone tissue engineering.  相似文献   
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