全文获取类型
收费全文 | 25576篇 |
免费 | 1443篇 |
国内免费 | 1038篇 |
专业分类
耳鼻咽喉 | 76篇 |
儿科学 | 471篇 |
妇产科学 | 501篇 |
基础医学 | 6405篇 |
口腔科学 | 294篇 |
临床医学 | 2220篇 |
内科学 | 2939篇 |
皮肤病学 | 354篇 |
神经病学 | 869篇 |
特种医学 | 512篇 |
外国民族医学 | 4篇 |
外科学 | 855篇 |
综合类 | 3301篇 |
现状与发展 | 2篇 |
预防医学 | 1899篇 |
眼科学 | 658篇 |
药学 | 4120篇 |
2篇 | |
中国医学 | 676篇 |
肿瘤学 | 1899篇 |
出版年
2024年 | 22篇 |
2023年 | 166篇 |
2022年 | 379篇 |
2021年 | 480篇 |
2020年 | 534篇 |
2019年 | 542篇 |
2018年 | 478篇 |
2017年 | 545篇 |
2016年 | 653篇 |
2015年 | 676篇 |
2014年 | 1188篇 |
2013年 | 1519篇 |
2012年 | 1285篇 |
2011年 | 1546篇 |
2010年 | 1148篇 |
2009年 | 1171篇 |
2008年 | 1180篇 |
2007年 | 1273篇 |
2006年 | 1135篇 |
2005年 | 1134篇 |
2004年 | 1072篇 |
2003年 | 926篇 |
2002年 | 858篇 |
2001年 | 751篇 |
2000年 | 656篇 |
1999年 | 596篇 |
1998年 | 563篇 |
1997年 | 573篇 |
1996年 | 520篇 |
1995年 | 538篇 |
1994年 | 409篇 |
1993年 | 387篇 |
1992年 | 365篇 |
1991年 | 314篇 |
1990年 | 293篇 |
1989年 | 236篇 |
1988年 | 244篇 |
1987年 | 198篇 |
1986年 | 208篇 |
1985年 | 270篇 |
1984年 | 209篇 |
1983年 | 189篇 |
1982年 | 160篇 |
1981年 | 116篇 |
1980年 | 105篇 |
1979年 | 91篇 |
1978年 | 45篇 |
1977年 | 39篇 |
1976年 | 12篇 |
1974年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
目的 探讨Y染色体无精症因子C区(azoospermia factor C,AZFe)无精症缺失基因(deleted-in-azoospermia,DAZ)家族基因拷贝缺失与中国男性原发不育之间的关系。方法 运用多重PCR与PCR-RFLP检测技术,对210例已生育男性、216例原发无精症与189例严重少精症患者Y染色体AzFc区域DAZ基因家族的基因拷贝数进行分析。结果 在所有已生育男性中未检出DAZ基因拷贝的完全或部分缺失,而在原发无精症与严重少精症患者中DAZ基因拷贝完全缺失率分别为8.8%和12.2%,DAZ1/DAZ2共缺失率分别为8.3%和5.3%。结论 在中国男性原发无精症与严重少精症患者中存在较高频率的DAZ基因拷贝缺失现象,提示Y染色体AZFc区域DAZ基因家族基因拷贝的完全与部分缺失是中国男性原发不育的遗传高风险因子。 相似文献
102.
Jonas Bergstrm Mahmood Ahmed Jian Li Tashfeen Ahmad Andris Kreicbergs Mariana Spetea 《Journal of orthopaedic research》2006,24(6):1193-1199
Using immunohistochemical and biochemical techniques, the occurrence of endogenous opioid peptides and their receptors in normal rat bone and joint tissues was investigated. Opioid receptors were detected, quantified, and characterized in homogenates from capsule/synovium and periosteum using radioligand binding assays. Receptor binding of the nonselective opioid [3H]naloxone to tissue homogenates was stereospecific and saturable, showing similar characteristics to that of brain tissue, although with lower binding capacities. By immunohistochemistry, the neuronal occurrence of four different enkephalins was demonstrated in synovium, bone marrow, periosteum, and juxta-articular bone, whereas no neuronal dynorphin immunoreactivity was detected. Double-staining studies disclosed that enkephalins coexisted with substance P in primary afferent fibers. The applied techniques can be used to assess changes in the distribution of endogenous opioids and their receptors in joint tissues in conditions associated with pain and inflammation. The endogenous opioid system now demonstrated might be targeted and exploited therapeutically to obtain peripheral control of symptoms in joint disorders. 相似文献
103.
Terry R. McGuire 《Behavior genetics》1992,22(4):453-467
Chromosome analysis has been widely used as a first step in eclucidating the genetic architecture of several behaviors ofDrosophila melanogaster. These chromosome studies have generally used incomplete designs or fairly simple statistical analyses. Here I reanalyze two data sets on geotaxis from Pyle (1978) and Ksander (1966) using a biometrical genetic design. Results from the biometrical genetic reanalysis suggest that individual differences in geotaxis might be due to genes on all three major chromosomes which show extensive epistatic interactions. 相似文献
104.
甘草甜素和甘草酸单铵促进IL-2增强NK活性的研究 总被引:1,自引:0,他引:1
本实验采用乳酸脱氢酶释放法研究甘草甜素和甘草酸单铵对人外周血NK细胞活性的影响。结果表明,甘草甜素和甘草酸单铵本身无增强NK细胞活性的作用,但可明显促进IL-2增强NK活性,这种增强作用与甘草甜素和甘草酸单铵的浓度有关。 相似文献
105.
应用细胞遗传学和皮纹分析方法对142例先天性智能发育不全患儿进行了研究。其中,120例正常核型,22例异常核型。异常核型46,XY,t(1;3;21)(1pter→1q32.1∶∶21p11.2→21qter;3 qter→3p26.2∶∶1 q32.1→1 qter)和45,X/45,X,-22,+der(22)t(Y;22)(22qter→22p11.1∶∶Yq11.1→Yq11.2)两种核型国内尚未见报道。皮纹分析结果表明56.7%的患者有1项以上异常皮纹;染色体异常患者均有2项以上异常皮纹;先天愚型患者有“特定”的皮纹改变。 相似文献
106.
Humoral immunity to Malassezia furfur serovars A, B and C in patients with pityriasis versicolor, seborrheic dermatitis and controls 总被引:2,自引:0,他引:2
H. R. Ashbee A. Fruin K. T. Holland W. J. Cunliffe E. Ingham 《Experimental dermatology》1994,3(5):227-233
Abstract This study examined the humoral immune responses to Malassezia furfur serovars A, B and C of 10 patients with pityriasis versicolor, 10 patients with seborrheic dermatitis and 20 age- and sex-matched controls. A transferable solid-phase ELISA was used to determine titres of total Igs, IgM, IgA and IgG specific to M. furfur serovars A, B and C. The results demonstrated that patients with seborrheic dermatitis had a significantly higher litre of total Igs to serovar A than patients with pityriasis versicolor; and that patients with seborrheic dermatitis had a significantly higher litre of IgA to serovar C than patients with pityriasis versicolor. The litres of total Igs for controls and patienls with seborrheic dermatitis were significantly lower to serovar B than to serovar C. A modified TSP ELISA was used to determine the titres of the IgG subclasses. Titres of IgG 1,3,4 to serovar B were significantly higher in seborrheic dermatitis patients than pityriasis versicolor patients and litres of IgG3, to serovar A were significantly higher in seborrheic dermatitis patients than pityriasis versicolor patients. However, despite the differences between the patient groups, none of these results was significantly different to those of controls. Thus, this study did not demonstrate any differences in humoral immunity of patients suffering from Malassezia-associated dermatoses when compared to normal controls. These results may suggest that the humoral immune response to M. furfur is not related to the pathogenesis of Malassezia-associated dermatoses, but simply to the carriage of M. furfur on the skin. 相似文献
107.
本文对新型有机磷农药,25%乙基硫环磷进行了Ames及微核两项诱变性试验研究。Ames试验中,无论是否加入S9活化系统,25%乙基硫环磷均未能诱发回变菌落数的增加;微核试验的各剂量组PCE微核率也较低,(2‰~3‰),与阴性对照相比无显著性差异。 相似文献
108.
D. A. Basketter E. W. Scholes M. Cumberbatch C. D. Evans I. Kimber 《Contact dermatitis》1992,27(4):209-213
The guinea pig maximization test (GPMT) has proven to be a valuable tool for the identification of the skin sensitization potential of chemicals. The method identifies a hazard which can lead in the EC to compulsory labelling of that chemical. In the present study, data on sulphanilic acid derived from the GPMT has been compared with results from a second guinea pig assay (the cumulative contact enhancement test) and the murine local lymph node assay, both of which require only topical application of chemical. Except for the GPMT, no test identified any sensitizing activity associated with exposure to sulphanilic acid. These latter results are consistent with the experience gained from substantial human exposure in an occupational setting and from which no cases of allergic contact dermatitis to sulphanilic acid have arisen over a 20-year period. In consequence, it is questioned which test protocol in practice has given the more accurate identification of sensitization hazard relevant to man. 相似文献
109.
Triploid origin of the gibel carp as revealed by 5S rDNA localization and chromosome painting 总被引:2,自引:0,他引:2
5S ribosomal DNA (rDNA) was isolated and sequenced from the gibel carp Carassius auratus gibelio with 162 chromosomes and crucian carp Carassius auratus with 100 chromosomes, and fluorescent probes for chromosome localization were prepared to ascertain the ploidy origin and
evolutionary relationship between the two species. Using fluorescence in-situ hybridization (FISH), major 5S rDNA signals were localized to the short arms of three subtelocentric chromosomes in the gibel
carp and to the short arms of two subtelocentrics in the crucian carp. In addition, some minor signals were detected on other
chromosomes of both species. Simultaneously, six chromosomes were microdissected from the gibel carp metaphase spreads using
glass needles, and the isolated chromosomes were amplified in vitro by degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR). Significantly, when the DOP-PCR-generated probes
prepared from each single chromosome were hybridized, three same-sized chromosomes were painted in each gibel carp metaphase,
whereas only two painted chromosomes were observed in each crucian carp metaphase spread. The data indicate that gibel carp
is of triploid origin in comparison with diploid crucian carp. 相似文献
110.