全文获取类型
收费全文 | 31989篇 |
免费 | 2615篇 |
国内免费 | 177篇 |
专业分类
耳鼻咽喉 | 323篇 |
儿科学 | 1108篇 |
妇产科学 | 726篇 |
基础医学 | 3723篇 |
口腔科学 | 654篇 |
临床医学 | 3089篇 |
内科学 | 6806篇 |
皮肤病学 | 548篇 |
神经病学 | 2471篇 |
特种医学 | 1014篇 |
外科学 | 4781篇 |
综合类 | 812篇 |
一般理论 | 16篇 |
预防医学 | 2131篇 |
眼科学 | 1335篇 |
药学 | 2414篇 |
1篇 | |
中国医学 | 141篇 |
肿瘤学 | 2688篇 |
出版年
2023年 | 231篇 |
2022年 | 368篇 |
2021年 | 785篇 |
2020年 | 498篇 |
2019年 | 725篇 |
2018年 | 826篇 |
2017年 | 587篇 |
2016年 | 688篇 |
2015年 | 787篇 |
2014年 | 1060篇 |
2013年 | 1262篇 |
2012年 | 2063篇 |
2011年 | 2124篇 |
2010年 | 1216篇 |
2009年 | 1064篇 |
2008年 | 1848篇 |
2007年 | 1805篇 |
2006年 | 1662篇 |
2005年 | 1591篇 |
2004年 | 1577篇 |
2003年 | 1394篇 |
2002年 | 1255篇 |
2001年 | 1143篇 |
2000年 | 1031篇 |
1999年 | 880篇 |
1998年 | 316篇 |
1997年 | 246篇 |
1996年 | 215篇 |
1995年 | 216篇 |
1994年 | 194篇 |
1993年 | 172篇 |
1992年 | 519篇 |
1991年 | 483篇 |
1990年 | 441篇 |
1989年 | 402篇 |
1988年 | 364篇 |
1987年 | 337篇 |
1986年 | 333篇 |
1985年 | 326篇 |
1984年 | 223篇 |
1983年 | 206篇 |
1982年 | 147篇 |
1981年 | 107篇 |
1980年 | 112篇 |
1979年 | 161篇 |
1978年 | 93篇 |
1977年 | 103篇 |
1976年 | 70篇 |
1974年 | 85篇 |
1973年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
942.
Sterling Richard K. King Wendy C. Khalili Mandana Kleiner David E. Hinerman Amanda S. Sulkowski Mark Chung Raymond T. Jain Mamta K. Lisker-Melman M auricio Wong David K. Ghany Marc G. 《Digestive diseases and sciences》2022,67(2):676-688
Digestive Diseases and Sciences - There are limited data on noninvasive methods to identify hepatic steatosis in coexisting hepatitis B virus (HBV) infection. To evaluate the diagnostic performance... 相似文献
943.
Urokinase-type plasminogen activator is a preferred substrate of the human epithelium serine protease tryptase epsilon/PRSS22 总被引:1,自引:0,他引:1
Yasuda S Morokawa N Wong GW Rossi A Madhusudhan MS Sali A Askew YS Adachi R Silverman GA Krilis SA Stevens RL 《Blood》2005,105(10):3893-3901
Tryptase epsilon is a member of the chromosome 16p13.3 family of human serine proteases that is preferentially expressed by epithelial cells. Recombinant pro-tryptase epsilon was generated to understand how the exocytosed zymogen might be activated outside of the epithelial cell, as well as to address its possible role in normal and diseased states. Using expression/site-directed mutagenesis approaches, we now show that Lys20, Cys90, and Asp92 in the protease's substrate-binding cleft regulate its enzymatic activity. We also show that Arg(-1) in the propeptide domain controls its ability to autoactivate. In vitro studies revealed that recombinant tryptase epsilon possesses a restricted substrate specificity. Once activated, tryptase epsilon cannot be inhibited effectively by the diverse array of protease inhibitors present in normal human plasma. Moreover, this epithelium protease is not highly susceptible to alpha1-antitrypsin or secretory leukocyte protease inhibitor, which are present in the lung. Recombinant tryptase epsilon could not cleave fibronectin, vitronectin, laminin, single-chain tissue-type plasminogen activator, plasminogen, or any prominent serum protein. Nevertheless, tryptase epsilon readily converted single-chain pro-urokinase-type plasminogen activator (pro-uPA/scuPA) into its mature, enzymatically active protease. Tryptase epsilon also was able to induce pro-uPA-expressing smooth muscle cells to increase their migration through a basement membrane-like extracellular matrix. The ability to activate uPA in the presence of varied protease inhibitors suggests that tryptase epsilon plays a prominent role in fibrinolysis and other uPA-dependent reactions in the lung. 相似文献
944.
Tsang KW Tipoe GL Mak JC Sun J Wong M Leung R Tan KC MedStat CK Ho JC Ho PL Rutman A Lam WK 《Respiratory medicine》2005,99(3):290-297
It has been suggested that patients with bronchiectasis might have increased central microtubular orientation angle (CMOA), which leads to poor coordination of ciliary beating, and consequently impairment of airway defence. We have employed transmission electron microscopy to assess CMOA of ciliated nasal mucosa in a cohort of 133 (81F, 56.8+/-16.1yr) stable bronchiectasis and 59 healthy subjects (30F, 49.3+/-22.1yr). There was no significant difference in CMOA between bronchiectasis (13.2 degree) and control subjects (13.0 degree, P=0.82). There was no significant difference in CMOA among patients according to the etiology of bronchiectasis, presence of nasal symptoms, or sputum status of Pseudomonas aeruginosa infection. Patients with more severe bronchiectasis, i.e. those with FEV(1) <60%, FVC <60%, or more than 4 bronchiectatic lung lobes, had significantly lower CMOA than their counterparts (P<0.05). There was no correlation between CMOA with age, 24h sputum volume, exacerbation frequency, FEV(1), FVC, or the number of bronchiectatic lung lobes (P>0.05). CMOA correlated with ciliary beat frequency (negative), and the percent of cilia showing ultrastructural or microtubular defects (P<0.05). Central microtubular orientation angle does not correlate with clinically important parameters, in contrary to the results reported by previously published smaller scale studies. 相似文献
945.
Objectives
We developed and tested a training method for basic life support incorporating defibrillator feedback during simulated cardiac arrest (CA) to determine the impact on the quality and retention of CPR skills.Methods
298 subjects were randomized into 3 groups. All groups received a 2 h training session followed by a simulated CA test scenario, immediately after training and at 3 months. Controls used a non-feedback defibrillator during training and testing. Group 1 was trained and tested with an audiovisual feedback defibrillator. During training, Group 1 reviewed quantitative CPR data from the defibrillator. Group 2 was trained as per Group 1, but was tested using the non-feedback defibrillator. The primary outcome was difference in compression depth between groups at initial testing. Secondary outcomes included differences in rate, depth at retesting, compression fraction, and self-assessment.Results
Groups 1 and 2 had significantly deeper compressions than the controls (35.3 ± 7.6 mm, 43.7 ± 5.8 mm, 42.2 ± 6.6 mm for controls, Groups 1 and 2, P = 0.001 for Group 1 vs. controls; P = 0.001 for Group 2 vs. controls). At three months, CPR depth was maintained in all groups but remained significantly higher in Group 1 (39.1 ± 9.9 mm, 47.0 ± 7.4 mm, 42.2 ± 8.4 mm for controls, Groups 1 and 2, P = 0.001 for Group 1 vs. control). No significant differences were noted between groups in compression rate or fraction.Conclusions
A simplified 2 h training method using audiovisual feedback combined with quantitative review of CPR performance improved CPR quality and retention of these skills. 相似文献946.
947.
Eric KamPui Lee Paul Poon ChunPong Yu Vivian WingYan Lee Vincent ChiHo Chung Samuel YeungShan Wong 《Journal of clinical hypertension (Greenwich, Conn.)》2022,24(5):529
Oral melatonin is a potential alternative treatment for hypertension and nocturnal hypertension. However, high‐quality and relevant meta‐analyses are lacking. This meta‐analysis aimed to investigate whether oral melatonin supplementation reduces daytime/asleep blood pressure and cardiovascular risk, improves sleep quality, and is well‐tolerated compared with placebo. Relevant articles were searched in multiple databases, including MEDLINE, EMBASE, CINAHL Complete, and the Cochrane Library, from their inception to June 2021. The included studies were randomized controlled trials recruiting patients with hypertension, using oral melatonin as the sole intervention, and investigating its effect on blood pressure. The mean out‐of‐office (including 24‐h, daytime, and asleep) systolic and diastolic blood pressures, sleep quality, and side effects were compared between the melatonin and placebo arms using pairwise random‐effect meta‐analyses. A risk of bias assessment was performed using the Cochrane risk‐of‐bias tool. Four studies were included in the analysis and only one study was considered to have a low risk of bias. No study reported on cardiovascular risk or outcomes. Only controlled‐release melatonin (not an immediate‐release preparation) reduced asleep systolic blood pressure by 3.57 mm Hg (95% confidence interval: –7.88 to .73; I2 = 0%). It also reduced asleep and awake diastolic blood pressure, but these differences were not statistically significant. Melatonin improves sleep efficacy and total sleep time and is safe and well‐tolerated. Due to the limited number of high‐quality trials, the quality of evidence was low to very low. Therefore, adequately powered randomized controlled trials on melatonin are warranted. 相似文献
948.
Marwa Chourabi Mei Shan Liew Shawn Lim Dorra H’mida-Ben Brahim Lobna Boussofara Liang Dai Pui Mun Wong Jia Nee Foo Badreddine Sriha Kim Samirah Robinson Simon Denil John EA Common Ons Mamaï Youcef Ben Khalifa Mathieu Bollen Jianjun Liu Mohamed Denguezli Carine Bonnard Bruno Reversade 《The Journal of investigative dermatology》2018,138(2):291-300
949.
Decrease of superficial serine and lactate in the stratum corneum due to repetitive frictional trauma 下载免费PDF全文
950.