全文获取类型
收费全文 | 47740篇 |
免费 | 3471篇 |
国内免费 | 196篇 |
专业分类
耳鼻咽喉 | 567篇 |
儿科学 | 998篇 |
妇产科学 | 966篇 |
基础医学 | 6600篇 |
口腔科学 | 1001篇 |
临床医学 | 4704篇 |
内科学 | 10010篇 |
皮肤病学 | 1077篇 |
神经病学 | 4548篇 |
特种医学 | 1961篇 |
外国民族医学 | 2篇 |
外科学 | 8708篇 |
综合类 | 480篇 |
一般理论 | 76篇 |
预防医学 | 2669篇 |
眼科学 | 938篇 |
药学 | 2795篇 |
中国医学 | 75篇 |
肿瘤学 | 3232篇 |
出版年
2023年 | 470篇 |
2022年 | 920篇 |
2021年 | 1722篇 |
2020年 | 1020篇 |
2019年 | 1357篇 |
2018年 | 1533篇 |
2017年 | 1032篇 |
2016年 | 1201篇 |
2015年 | 1381篇 |
2014年 | 1876篇 |
2013年 | 2185篇 |
2012年 | 3561篇 |
2011年 | 3503篇 |
2010年 | 1954篇 |
2009年 | 1733篇 |
2008年 | 2729篇 |
2007年 | 2786篇 |
2006年 | 2585篇 |
2005年 | 2405篇 |
2004年 | 2224篇 |
2003年 | 2030篇 |
2002年 | 1860篇 |
2001年 | 524篇 |
2000年 | 515篇 |
1999年 | 535篇 |
1998年 | 430篇 |
1997年 | 339篇 |
1996年 | 253篇 |
1995年 | 247篇 |
1994年 | 208篇 |
1993年 | 212篇 |
1992年 | 365篇 |
1991年 | 337篇 |
1990年 | 308篇 |
1989年 | 270篇 |
1988年 | 258篇 |
1987年 | 242篇 |
1986年 | 234篇 |
1985年 | 261篇 |
1984年 | 216篇 |
1983年 | 204篇 |
1982年 | 168篇 |
1981年 | 158篇 |
1980年 | 168篇 |
1979年 | 182篇 |
1978年 | 150篇 |
1977年 | 136篇 |
1976年 | 135篇 |
1974年 | 142篇 |
1973年 | 121篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Robert M. Levy Roman Saikovsky Evgeniya Shmidt Alexander Khokhlov Bruce P. Burnett 《Nutrition Research》2009
Flavocoxid (Limbrel), a proprietary mixture of flavonoid molecules (baicalin and catechin), was tested against a traditional nonsteroidal anti-inflammatory drug, naproxen, for the management of the signs and symptoms of moderate osteoarthritis (OA) in humans. Discomfort and global disease activity were used as the primary end points, and safety assessments were also taken for both treatments as a secondary endpoint. In this double-blind study, 103 subjects were randomly assigned to receive either flavocoxid [500 mg twice daily (BID)] or naproxen (500 mg BID) in a 1-month onset of action trial. Outcome measures included the short Western Ontario and McMaster University Osteoarthritis Index, subject Visual Analogue Scale for discomfort and global response, and investigator Visual Analogue Scale for global response and fecal occult blood. Both flavocoxid and naproxen showed significant reduction in the signs and symptoms of knee OA (P ≤ .001). There were no statistically detectable differences between the flavocoxid and naproxen groups with respect to any of the outcome variables. Similarly, there were no statistically detectable differences between the groups with respect to any adverse event, although there was a trend toward a higher incidence of edema and nonspecific musculoskeletal discomfort in the naproxen group. In this short-term pilot study, flavocoxid was as effective as naproxen in controlling the signs and symptoms of OA of the knee and would present a safe and effective option for those individuals on traditional nonsteroidal anti-inflammatory drugs or cyclooxygenase-2 inhibitors. A low incidence of adverse events was reported for both groups. 相似文献
22.
23.
24.
25.
Margaret J Bowers Nick J Orr Si Dempsey H Denis Alexander 《Blood coagulation & fibrinolysis》2006,17(5):409-411
We present a case of Bernard Soulier syndrome in a 9-year-old boy caused by a novel genetic mutation. This child was shown to be homozygous for a single nucleotide deletion (c.1077delG) in the GP1BA gene not previously reported. Clinically, the boy has become refractory to platelet transfusions with both allo-antibodies and iso-antibodies and a massive transfusion requirement for ongoing haemorrhage. We describe the critical role that the blood product transfusion continues to play in the management of Bernard Soulier syndrome and discuss therapeutic options in these patients. 相似文献
26.
In-vitro/in-vivo correlation of pulsatile drug release from press-coated tablet formulations: a pharmacoscintigraphic study in the beagle dog. 总被引:1,自引:0,他引:1
Manish Ghimire Fiona J McInnes David G Watson Alexander B Mullen Howard N E Stevens 《European journal of pharmaceutics and biopharmaceutics》2007,67(2):515-523
The aim of the current study was to investigate the in-vitro and in-vivo performance of a press-coated tablet (PCT) intended for time delayed drug release, consisting of a rapidly disintegrating theophylline core tablet, press-coated with barrier granules containing glyceryl behenate (GB) and low-substituted hydroxypropylcellulose (L-HPC). The PCTs showed pulsatile release with a lag time dependent upon the GB and L-HPC composition of the barrier layer. In-vivo gamma-scintigraphic studies were carried out for PCTs containing GB:L-HPC at 65:35 w/w and 75:25 w/w in the barrier layer in four beagle dogs, in either the fed or fasted state. The in-vivo lag time in both the fed and fasted states did not differ significantly (p>0.05) from the in-vitro lag time. Additionally, no significant difference (p<0.05) between in-vivo fed and fasted disintegration times was observed, demonstrating that in-vivo performance of the PCT was not influenced by the presence or absence of food in the gastrointestinal tract. A distinct lag time was obtained prior to the appearance of drug in plasma and correlated (R2=0.98) with disintegration time observed from scintigraphic images. However, following disintegration, no difference in pharmacokinetic parameters (AUC(0-6 dis), K(el), Cmax) was observed. The current study highlighted the potential use of these formulations for chronopharmaceutical drug delivery. 相似文献
27.
Summary Dozens of novel cysteine proteinases have been identified in positive single-stranded RNA viruses and, for the first time, in large double-stranded DNA viruses. The majority of these proteins are distantly related to papain or chymotrypsin and may be direct descendants of primordial proteolytic enzymes. Virus genome synthesis and expression, virion formation, virion entry into the host cell, as well as cellular architecture and functioning can be under the control of viral cysteine proteinases during infection. RNA virus proteinases mediate their liberation from giant multidomain precursors in which they tend to occupy conserved positions. These proteinases possess a narrow substrate specificity, can cleave in cis and in trans, and may also have additional, nonproteolytic functions. The mechanisms of catalysis, substrate recognition and RNA binding were highlighted by the recent analysis of the three-dimensional structure of the chymotrypsin-like cysteine proteinases of two RNA viruses. 相似文献
28.
Fix Joseph A. Alexander Jose Cortese Margot Engle Karen Leppert Paula Repta A. J. 《Pharmaceutical research》1990,7(4):384-387
Short-chain alkyl esters of L-dopa were administered to rats and mice via oral and rectal routes. Plasma L-dopa esters and L-dopa were determined in the systemic and portal circulation by HPLC. A comparison of isopropyl, butyl, and 4-hydroxybutyl esters of L-dopa demonstrated significantly higher levels of the esters in both systemic and portal blood samples following rectal administration than following oral administration. In most cases, oral administration resulted in nondetectable (<0.01 µg/ml) levels of the esters in plasma. Correspondingly, the plasma levels of L-dopa itself were consistently higher following rectal administration. At very high oral doses (500 mg L-dopa equivalents/kg body weight), systemic plasma levels of the butyl ester could be detected (1.25 µg/ml at 10 min), which might indicate saturation of the esterase activity of the small intestine. These studies indicate that the systemic availability of L-dopa from short-chain alkyl esters of L-dopa may be best optimized by rectal administration, which avoids the relatively high esterase activity characteristic of the small intestine. 相似文献
29.
30.
Claus Jacob Alexander Y. Safronov Sonia Wilson H.Allen O. Hill Tim F. Booth 《Journal of electroanalytical chemistry (Lausanne, Switzerland)》1997,431(1):7-10
A novel chiral redox-active ferrocene compound (FcVI) with amphiphilic properties has been synthesized. Cryogenic Transmission Electron Microscopy (cryo-TEM) has been used to estimate the shape and size of the FcVI aggregates in solution. Uni- and multi-lamellar vesicles (between 40 and 300 nm in diameter) were observed in water. Large particles (of more than 1 μm in diameter) with a hexagonal fine structure were found in 50 mM aqueous Na2SO4 solution. Sonication transformed the latter into ‘rosette’-like structures. Cyclic voltammetry has been employed to investigate the electrochemical properties of FcVI. The amphiphile adsorbed on graphite electrodes and a reversible electrochemical behaviour, characteristic of ferrocene, was observed with redox potentials between 330 and 350 mV. 相似文献