全文获取类型
收费全文 | 49597篇 |
免费 | 3974篇 |
国内免费 | 487篇 |
专业分类
耳鼻咽喉 | 561篇 |
儿科学 | 1343篇 |
妇产科学 | 833篇 |
基础医学 | 6933篇 |
口腔科学 | 740篇 |
临床医学 | 4833篇 |
内科学 | 10616篇 |
皮肤病学 | 1143篇 |
神经病学 | 3547篇 |
特种医学 | 1919篇 |
外国民族医学 | 16篇 |
外科学 | 6761篇 |
综合类 | 1390篇 |
现状与发展 | 2篇 |
一般理论 | 6篇 |
预防医学 | 3937篇 |
眼科学 | 1192篇 |
药学 | 3725篇 |
6篇 | |
中国医学 | 704篇 |
肿瘤学 | 3851篇 |
出版年
2023年 | 440篇 |
2022年 | 1056篇 |
2021年 | 1875篇 |
2020年 | 1078篇 |
2019年 | 1363篇 |
2018年 | 1671篇 |
2017年 | 1164篇 |
2016年 | 1253篇 |
2015年 | 1429篇 |
2014年 | 1807篇 |
2013年 | 2201篇 |
2012年 | 3289篇 |
2011年 | 3284篇 |
2010年 | 2003篇 |
2009年 | 1639篇 |
2008年 | 2504篇 |
2007年 | 2540篇 |
2006年 | 2314篇 |
2005年 | 2179篇 |
2004年 | 1939篇 |
2003年 | 1806篇 |
2002年 | 1696篇 |
2001年 | 1607篇 |
2000年 | 1545篇 |
1999年 | 1348篇 |
1998年 | 456篇 |
1997年 | 398篇 |
1996年 | 347篇 |
1995年 | 291篇 |
1994年 | 280篇 |
1993年 | 235篇 |
1992年 | 662篇 |
1991年 | 603篇 |
1990年 | 593篇 |
1989年 | 538篇 |
1988年 | 549篇 |
1987年 | 460篇 |
1986年 | 437篇 |
1985年 | 420篇 |
1984年 | 305篇 |
1983年 | 218篇 |
1982年 | 138篇 |
1981年 | 114篇 |
1979年 | 228篇 |
1978年 | 117篇 |
1977年 | 133篇 |
1976年 | 121篇 |
1974年 | 135篇 |
1973年 | 107篇 |
1972年 | 131篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
B Kerboul J Le Saout C Lefevre D Miroux L Fabre J F Le Noac'h J M Rogero B Courtois 《Journal de chirurgie》1986,123(6-7):428-434
Results of three therapeutic modalities used for the treatment of a homogeneous series of patients with a Pouteau Colles fracture are analyzed. Orthopedic treatment provided deceiving results. Pinning was, on the contrary, very effective, intrafocal pinning with immediate mobilization of the wrist appearing perfectly effective. Few complications were reported in contrast to plastered immobilizations. Good results were obtained in 80% of cases and functional recovery was rapid, indicating that this method represents undoubted progress when compared with conventional therapies. 相似文献
32.
Effect of acute tyrosine depletion in using a branched chain amino-acid mixture on dopamine neurotransmission in the rat brain. 总被引:1,自引:0,他引:1
Marisa Le Masurier Weite Oldenzeil Claire Lehman Philip Cowen Trevor Sharp 《Neuropsychopharmacology》2006,31(2):310-317
Central dopamine function is reduced by decreasing the availability of the catecholamine precursor, tyrosine, using a tyrosine-free amino acid mixture containing multiple large neutral as well as branched chain amino-acids, which compete with tyrosine for uptake into the brain. Current mixtures are cumbersome to make and administer, and unpalatable to patients and volunteers. Here, we investigate whether individual or limited amino-acid combinations could reduce brain tyrosine levels and hence dopamine function. Measurements of regional brain tyrosine levels, catecholamine and indoleamine synthesis (L-DOPA and 5-HTP accumulation, respectively) were used to identify an effective paradigm to test in neurochemical, behavioral and fos immunocytochemical models. Administration of leucine or isoleucine, or a mixture of leucine, isoleucine, and valine reduced tyrosine and 5-HTP, but not L-DOPA accumulation. A mixture of leucine, valine, and isoleucine supplemented with tryptophan reduced brain tyrosine and L-DOPA, but not 5-HTP. In microdialysis experiments this amino-acid mixture reduced basal and amphetamine-evoked striatal dopamine release, as well as amphetamine-induced hyperactivity. This mixture also reduced amphetamine-induced fos expression in striatal areas. In conclusion, the present study identified a small combination of amino acids that reduces brain tyrosine and dopamine function in a manner similar to mixtures of multiple amino acids. This minimal mixture may have use as a dopamine reducing paradigm in patient and volunteer studies. 相似文献
33.
Bone marrow cells in X-linked agammaglobulinemia express pre-B-specific genes (lambda-like and V pre-B) and present immunoglobulin V-D-J gene usage strongly biased to a fetal-like repertoire. 总被引:1,自引:1,他引:0 下载免费PDF全文
M Milili F Le Deist G de Saint-Basile A Fischer M Fougereau C Schiff 《The Journal of clinical investigation》1993,91(4):1616-1629
34.
35.
Automatic analysis of electromyography (EMG) signals, first operated in 1950 with analogic machines, steeply expanded from 1980 when fast computers and worthwhile programs became available. On-line measurement of response area and latency, averaging of low amplitude waves, fast sorting of motor unit potential shape parameters, computation of the “jitter” between two muscle fibers, turns/amplitude and spectral analysis of interferential pattern records, are some examples of programs currently offered in modern EMG machines. Other techniques are still reserved for research purposes: scanning EMG, decomposition of nerve and muscle compound potentials, measurement of the threshold and firing rate of motor units, trace analysis using tracking models. Finally, the credit for artificial intelligence systems (knowledge based systems, fuzzy logic, neuronal networks) is still not clearly stated. 相似文献
36.
Mice homozygous for the lpr mutation have B and T cell defects and develop autoantibodies, suggesting that lpr plays a role in their genesis. The lpr defect has been identified as a mutation in the apoptosis-associated Fas receptor (FasR) gene. To begin to define the role of FasR in B cells, we have surveyed FasR expression on B-lineage cells from early progenitors in the bone marrow through their maturation in the periphery. Contrary to some reports, we found that FasR is expressed on B cells at all stages of their development and is highest on germinal center B cells. FasR is not expressed on lpr/lpr-derived cells. These data are consistent with the idea that lpr/lpr mice have an intrinsic B cell defect that may be manifested in developing as well as peripheral B cells. An unexpected finding is that B-1 (CD5) B cells do not constitutively express FasR: FasR becomes detectable on B-1 B cells only after activation. 相似文献
37.
W T Yuh E T Tali H D Nguyen T M Simonson N A Mayr D J Fisher 《AJNR. American journal of neuroradiology》1995,16(2):373
PURPOSETo evaluate the effect of MR contrast dose versus delayed imaging time on the detection of metastatic brain lesions based on lesion size.METHODSContrast MR examinations with gadoteridol were obtained in 45 patients with brain metastases. The patients were divided into two groups: 16 received cumulative standard dose (0.1 mmol/kg) and 29 received cumulative triple dose (0.3 mmol/kg). Both groups were evaluated at two dose levels (lower dose and higher dose) with two separate injections. Each patient received an initial bolus injection of either 0.05 (cumulative standard dose) or 0.1 (cumulative triple dose) mmol/kg of gadoteridol to reach the lower-dose level and underwent imaging immediately and 10 and 20 minutes later. Thirty minutes after injection, an additional bolus injection of 0.05 (cumulative standard dose) or 0.2 (cumulative triple dose) mmol/kg was administered to reach the cumulative higher-dose level (cumulative standard dose, 0.1 mmol/kg; cumulative triple dose, 0.3 mmol). Images were acquired immediately.RESULTSThere was no difference in the detection rate for lesions larger than 10 mm among T2-weighted, lower-dose immediate and delayed, or immediate higher-dose images in both study groups. Lesions smaller than 10 mm had improved detection with delayed imaging in both study groups; however, the immediate higher-dose studies still had the highest detection rate.CONCLUSIONIn the evaluation of small central nervous system metastases, either delayed imaging after the injection of standard contrast dose or higher contrast dose may improve their detection, and therefore affect clinical management. Higher contrast dose (cumulative triple dose) studies appear to be more effective than delayed imaging with standard dose. 相似文献
38.
39.
40.
Because caffeine and nifedipine may have opposing effects on intracellular calcium concentration, a possible interaction between these agents on blood pressure and heart rate was examined. With a randomized, double-blind, crossover design, 10 normal, caffeine-abstaining subjects received caffeine, 300 mg, or placebo followed by nifedipine, 10 mg, or placebo. Caffeine increased blood pressure, whereas nifedipine reduced it and caused a reflex increase in heart rate. With caffeine pretreatment, nifedipine decreased blood pressure significantly more than with placebo pretreatment. However, nifedipine reduced blood pressure to the same absolute level on both the caffeine and placebo pretreatment days. The reflex increase in heart rate after nifedipine was not affected by prior caffeine or placebo administration. Caffeine pretreatment does not alter the cardiovascular responses to nifedipine but the pressor effect of caffeine is completely reversed by subsequent nifedipine administration. 相似文献