全文获取类型
收费全文 | 19685篇 |
免费 | 1503篇 |
国内免费 | 602篇 |
专业分类
耳鼻咽喉 | 55篇 |
儿科学 | 214篇 |
妇产科学 | 171篇 |
基础医学 | 1773篇 |
口腔科学 | 147篇 |
临床医学 | 750篇 |
内科学 | 2731篇 |
皮肤病学 | 263篇 |
神经病学 | 887篇 |
特种医学 | 382篇 |
外国民族医学 | 1篇 |
外科学 | 1142篇 |
综合类 | 3062篇 |
预防医学 | 793篇 |
眼科学 | 188篇 |
药学 | 3181篇 |
1篇 | |
中国医学 | 5204篇 |
肿瘤学 | 845篇 |
出版年
2024年 | 71篇 |
2023年 | 240篇 |
2022年 | 458篇 |
2021年 | 559篇 |
2020年 | 490篇 |
2019年 | 784篇 |
2018年 | 774篇 |
2017年 | 604篇 |
2016年 | 487篇 |
2015年 | 542篇 |
2014年 | 953篇 |
2013年 | 1105篇 |
2012年 | 1193篇 |
2011年 | 1259篇 |
2010年 | 973篇 |
2009年 | 907篇 |
2008年 | 940篇 |
2007年 | 1021篇 |
2006年 | 914篇 |
2005年 | 694篇 |
2004年 | 617篇 |
2003年 | 647篇 |
2002年 | 532篇 |
2001年 | 530篇 |
2000年 | 365篇 |
1999年 | 301篇 |
1998年 | 216篇 |
1997年 | 200篇 |
1996年 | 121篇 |
1995年 | 114篇 |
1994年 | 95篇 |
1993年 | 81篇 |
1992年 | 71篇 |
1991年 | 66篇 |
1990年 | 64篇 |
1989年 | 55篇 |
1987年 | 52篇 |
1985年 | 273篇 |
1984年 | 389篇 |
1983年 | 265篇 |
1982年 | 269篇 |
1981年 | 244篇 |
1980年 | 204篇 |
1979年 | 220篇 |
1978年 | 171篇 |
1977年 | 97篇 |
1976年 | 165篇 |
1975年 | 135篇 |
1974年 | 90篇 |
1973年 | 82篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
目的 观察腹腔镜胆囊切除术 (LaparoscopicCholecystectomy ,L .C)后钛夹在腹腔内异位。方法 前瞻性对2 0 0 2年 1~ 5月间 6 0例L .C病人进行追踪观察临床表现 ,采用B超、腹部X线检查等方法 ,观察钛夹位置的变化与肝外胆管的关系。结果 6 0例L .C后病人中 5例钛夹发生位置改变。结论 ①钛夹在体内 ,对胆道无压迫、无胆漏 ;②观察钛夹异位 ,以采用B超为最简单、经济的方法。 相似文献
12.
L-精氨酸对高原肺水肿患者血液流变学的作用 总被引:3,自引:0,他引:3
目的:探讨雾化吸入左旋精氨酸(L-Arg)对高原肺水肿患者血液流变学的影响。方法:在海拔3700m高原,采用氧气驱动雾化吸入L-Arg,治疗高原肺水肿(HAPE)患者9例(L-Arg组),将吸入低浓度一氧化氮(NO)混合气治疗的另外8例高原肺水肿患者(NO组)作对照,分别测定患者的红细胞压积(HCT)、血液粘度(ηb)、血浆粘度(ηp)、还原粘度(ηr)、红细胞刚性指数(IR)、红细胞变形系数(TK)、红细胞聚集系数(VAI)和血栓形成系数(TFL)等血液流变学指标。结果:NO组和L-Arg组治疗后较治愈前ηb、ηp、ηr、VAI、TFL均降低显著(P〈0.05~0.01),而HCT、TK、IR无统计学差异(P〉0.05);NO组与L-Arg组比较,各指标均无统计学差异(P〉0.01)。结论:L-Arg治疗HAPE有效,通过提高NO水平而改善血液循环,且经济简便,易于推广应用。 相似文献
13.
The influence of a fraction obtained from Galeopsis ladanum L. on the central nervous system of rodents was examined. The results of these investigations show that the fraction impeded CNS activity. It is practically nontoxic and at a dose of 2000 mg/kg i.p. it does not have a soporific influence on mice. It reduces considerably the spontaneous locomotor activity of mice as well as the locomotor activity of mice stimulated by caffeine, but did not influence the locomotor activity induced by amphetamine. The extract did not exhibit a synergetic effect with barbiturates. The results suggest that the pharmacological activity of the extract resembled the activity of drugs which generally depress the CNS, being on the border between ataractic and sedative drugs. 相似文献
14.
Franciszek Burdan Zofia Siezieniewska Ryszard Maciejewski Barbara Madej Elzbieta Radzikowska Zbigniew Wojtowicz 《Experimental and toxicologic pathology》2002,53(6):453-459
The aim of the study was to establish the influence of short-time omeprazole administration on liver function and morphology. Omeprazole was administered intraperitoneally, twice daily, for 3 days to male Wistar rats in two doses: 0.571 mg/kg and 5.71 mg/kg. Control animals were treated with physiological saline. Half of the animals were sacrificed 12 hours after the last injection. The remaining rats were raised for another 6 weeks, without any xenobiotics, and sacrificed on the 47th day of the experiment. The activity of free and bound fractions of hepatic acid phosphatase, beta-galactosidase, beta-N-acetyl-glucosaminidase, cathepsin B, D and L, lipase, and sulphatase were determined spectrophotometrically in homogenates of the liver. The liver sections were examined by light microscopy with hematoxylin-eosin, azan, and periodic acid-Schiff stains. Marginally significant (p < 0.1) differences in activity of free sulphatase fraction, and free and bound fractions of beta-galactosidase were found in animals exposed to the higher dose of omeprazole and sacrificed 12 hours after the last injection. Enzymatic profiles were normalised during the next 6 weeks. Histological evaluation revealed small degenerative and adaptive changes in all examined groups. It could be concluded that observed differences of hepatic lysosomal enzyme activities were the result of accompanied chemical-induced peritonitis as previously reported, and not a direct drug-toxic effect. 相似文献
15.
从兔网织红细胞提纯的红细胞分化调节因子(erythroid differentiation factor,EDF),能对体外培养的自发转化成纤维细胞系L929及人鼻咽癌细胞系KB产生作用。当EDF剂量为0.10μg/ml时,可引起L929细胞形态发生改变,并有细胞核固缩现象。第2d的细胞生长抑制率为64.86%,软琼脂集落形成率为0;第5d时细胞增殖为负值。~3H-TdR掺入率明显降低。EDF剂量为0.15μg/ml时,对KB细胞生长已有抑制作用。EDF剂量达0.30μg/ml时,生长抑制明显。以上结果证明了EDF对恶性细胞具有增殖抑制作用。这种作用对不同种类细胞敏感性不同,并且与剂量呈正相关。 相似文献
16.
Chemically induced mutants of an I-Ak,d expressing antigen-presenting B-cell--B-lymphoma hybridoma have recently been generated by immunoselection in vitro and were found to possess alterations in some of their serologically and functionally defined I-Ak region dependent functions. In order to identify at the structural level the origin of the differences in serological and functional properties of these mutants, I-Ak molecules from several of these mutant hybridomas were compared biochemically to wild-type I-Ak polypeptides by two-dimensional gel electrophoresis and high-pressure liquid chromatographic tryptic peptide analyses. Two-dimensional gel electrophoresis indicated that no major structural alterations, resulting in changes in mol. wt or charge, had occurred in the Ak alpha or Ak beta polypeptides from the mutant cells. Likewise, Ak alpha peptide maps of the mutants were indistinguishable from the normal Ak alpha peptide maps. However, two of the three mutants studied did exhibit one additional peptide in their Ak beta peptide maps. These results suggest that the major deficiencies in T-cell-activating functions of these mutants are a result of a limited alteration in the Ak beta polypeptide primary structure. 相似文献
17.
The familial prevalence in second-degree relatives of patients with anxiety neurosis (panic disorder) 总被引:1,自引:0,他引:1
A family history study of second-degree relatives of 19 patients with anxiety neurosis (panic disorder) and 19 controls showed a morbidity risk of 9.5% among the former compared with 1.4% among the latter. These risks were approximately half those found among first-degree relatives. Female relatives were at higher risk for anxiety neurosis. The risk for other psychiatric illnesses did not differ between the relatives of anxiety neurosis and controls. 相似文献
18.
The present study was designed to investigate the relationship between intra-and inter-individual differences in arousal level and performance on both critical flicker fusion frequency and figural reversal tasks. Forty male undergraduate Ss were used. Electrical skin conductance was used as the indicant of arousal level. For the intra-individual comparisons white noise was used to increase the Ss’arousal levels. Significant inverted U-shaped relationships were found between both flicker fusion thresholds and rates of figural reversal and skin conductance between individuals. A significant curvilinear relationship was found between rates of figural reversal and level of conductance within individuals. No significant curvilinear relationship was found between flicker fusion thresholds and level of conductance within individuals. 相似文献
19.
Genome of the European elk papillomavirus (EEPV) 总被引:1,自引:0,他引:1
The genome of the European elk papillomavirus (EEPV) was found to be 8,095 base pairs (bp) long and its genetic organization was similar to that of other papillomaviruses. Ten open reading frames (ORFs), designated E1-E7 and L1-L3, were identified in the genome, all located on one strand. The presence of the L3 ORF is rare among the papillomaviruses and to date has only been identified in the genomes of EEPV, the deer papillomavirus (DPV) and the Cottontail papillomavirus (CRPV). The ORF is well conserved beteeen DPV and EEPV with regard to both length and sequence. Potential promoter regions were identified at the 5-end of the E6 ORF, at the 3-end of the E1 ORF and downstream of the L1 ORF. Furthermore, two potential polyadenylation signals were found, one located in the long control region (LCR), downstream of the L1 ORF, and another preceding the L2 ORF. The EEVP genome is closely related to the genome of the DPV, the most highly conserved regions being ORFs E1 (70%), E5 (69%), and L1 (74%). 相似文献
20.
In the search for a serology tool for the diagnosis of nonpatent as well as patent infections with Oesophagostomum dentatum in pigs a water-soluble, unglycosilated antigen of about 30 kDa specific for the third-stage larvae of the parasite was purified
by ion-exchange chromatography. In Western blots, the antigen was first detected by antibodies at day 7 postinfection. Cross-reactivity
with O. quadrispinulatum, Ascaris suum, or Trichuris suis was not detected. It is suggested that this protein is a suitable tool for the species-specific serodiagnosis of O. dentatum infection in pigs.
Received: 15 June 1998 / Accepted: 28 September 1998 相似文献