全文获取类型
收费全文 | 88343篇 |
免费 | 7878篇 |
国内免费 | 2769篇 |
专业分类
耳鼻咽喉 | 1293篇 |
儿科学 | 1372篇 |
妇产科学 | 1224篇 |
基础医学 | 12954篇 |
口腔科学 | 1333篇 |
临床医学 | 9050篇 |
内科学 | 16385篇 |
皮肤病学 | 2424篇 |
神经病学 | 6732篇 |
特种医学 | 4517篇 |
外国民族医学 | 7篇 |
外科学 | 9821篇 |
综合类 | 5716篇 |
现状与发展 | 6篇 |
一般理论 | 18篇 |
预防医学 | 5610篇 |
眼科学 | 2236篇 |
药学 | 8558篇 |
18篇 | |
中国医学 | 2900篇 |
肿瘤学 | 6816篇 |
出版年
2024年 | 230篇 |
2023年 | 993篇 |
2022年 | 2380篇 |
2021年 | 3349篇 |
2020年 | 2039篇 |
2019年 | 2459篇 |
2018年 | 2706篇 |
2017年 | 2246篇 |
2016年 | 2848篇 |
2015年 | 3811篇 |
2014年 | 4502篇 |
2013年 | 4846篇 |
2012年 | 6976篇 |
2011年 | 6897篇 |
2010年 | 4300篇 |
2009年 | 3499篇 |
2008年 | 4620篇 |
2007年 | 4619篇 |
2006年 | 4163篇 |
2005年 | 3982篇 |
2004年 | 3221篇 |
2003年 | 3122篇 |
2002年 | 2782篇 |
2001年 | 2003篇 |
2000年 | 1782篇 |
1999年 | 1485篇 |
1998年 | 766篇 |
1997年 | 714篇 |
1996年 | 555篇 |
1995年 | 505篇 |
1994年 | 446篇 |
1993年 | 403篇 |
1992年 | 750篇 |
1991年 | 769篇 |
1990年 | 676篇 |
1989年 | 692篇 |
1988年 | 672篇 |
1987年 | 644篇 |
1986年 | 561篇 |
1985年 | 541篇 |
1984年 | 416篇 |
1983年 | 338篇 |
1982年 | 254篇 |
1981年 | 242篇 |
1980年 | 212篇 |
1979年 | 315篇 |
1978年 | 260篇 |
1977年 | 186篇 |
1974年 | 207篇 |
1973年 | 226篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
R Cotter R Johnson M Tumbelson J Dexter S Young C A Taylor F Cosmas W B Rowe L Lin 《JPEN. Journal of parenteral and enteral nutrition》1988,12(2):121-126
The ability of soybean oil lipid emulsions to affect essential fatty acid deficiency (EFAD) and plasma fatty acid distribution was studied in neonatal pigs. The test animals were maintained on a fat-free diet prior to administration of lipid emulsion. Plasma and red blood cell (RBC) membrane levels of essential [linoleic (C-18:2 omega 6) and arachidonic (C-20:4 omega 6)] and nonessential [palmitic (C-16, palmitoleic (C-16:1 omega 7), stearic (C-18), and oleic (C-18:1 omega 9)] fatty acids and the triene:tetraene ratio [5,8,11-eicosatrienoic acid (C-20:3 omega 9):arachidonic acid (C-20:4 omega 6)] were monitored to ascertain the establishment of EFAD and its correction. Nonessential fatty acids were studied, as these components of lipid therapy have received little attention. Results indicate that soybean oil emulsions are effective in reversing fatty acid profiles found in EFAD, and both essential and nonessential fatty acids are under strict metabolic control. 相似文献
83.
Eain M. Cornford Deborah Young James W. Paxton 《Cancer chemotherapy and pharmacology》1992,29(6):439-444
Summary The blood-brain barrier penetration of amsacrine and its analogs 9-({2-methoxy-4-[(methylsulfonyl)-amino]phenyl}amino)-,5-dimethyl-4-acridine carboxamide (CI-921) and M-[2-(dimethylamino)ethyl]-acridine-4-carboxamide (AC) was measured in the barbiturate-anesthetized mouse. After intracarotid administration, AC was almost completery extracted (90%) in a single transit through the brain capillaries, whereas CI-921 (20%) and amsacrine (15%) were moderately extracted. AC is retained in the brain; no loss of AC from the brain was apparent at 1, 2, 4, or 8 min after injection. In contrast, after intraportal administration, 75% of the AC, 94% of the CI-921, and 57% of the amsacrine was extracted in a single transit through the hepatic vasculature. Rather than being retained in the mouse liver, these acridine antitumor agents show time-dependent loss (t
1/2=10 min for amsacrine and AC, 24 min for CI-921). We conclude that unlike most antitumor agents, these acridine drugs appear to penetrate the blood-brain barrier readily.This study was supported by the Auckland Medical Research Foundation (New Zealand), by the Medical Research Foundation (New Zealand), by the National Science Foundation (United States/New Zealand Cooperative Science Program), by the United States Veterans Administration, and by NIH grant NS 25554 相似文献
84.
The association between nitrate levels in public and private sources of drinking water and gastric cancer mortality in Wisconsin was investigated in a case-control study. All gastric cancer deaths of Wisconsin residents from 1982 through 1985 were compared with deaths from other causes (controls), and nitrate levels in the home drinking water of these residents were determined. Nitrate measures for public sources were obtained from historic nitrate data from municipal sources that existed in 1970. Nitrate measures for private water sources were obtained by testing the wells individually at the existing residences. Controls were matched individually to gastric cancer cases with respect to sex, year of birth, year of death, Wisconsin birth, and Wisconsin residency at the time of death. Matched-pair analyses were performed on the paired data, and the following levels of nitrate-nitrogen exposure were used as indicators of exposure: 0.5, 2.5, 5.0, and 10.0 mg/l. Matched-pair analysis was also performed for which private water supply constituted exposure. Odds ratios and 95% confidence intervals were, respectively, 0.92 (0.75, 1.12); 0.97 (0.74, 1.35); 0.86 (0.69, 1.08); 1.50 (0.12, 18.25); and 1.09 (0.82, 1.47) for exposure to private well-water sources. These results did not indicate an increased risk of gastric cancer at any level. 相似文献
85.
益母草防治初发期急性肾小管坏死的实验研究 总被引:13,自引:3,他引:10
SD成年雄性大鼠,禁止16小时,肌注甘油引起急性肾小管坏死(ATN),于其初发期给予不同药液,观察到益母草组3、24及48小时Bcr升高值,24及48小时BUN升高值均明显低于自来水组和单纯禁水组,而与校正对照异搏停组近似,肾组织损伤程度亦明显减轻。结果表明,益母草对初发期急性肾小管坏死(IATN)有一定的防治作用。 相似文献
86.
We tested the hypothesis that suppression of inward calcium current in presynaptic terminals is the cause of failure of synaptic transmission early during cerebral hypoxia. Postsynaptic responses in CA1 zone of hippocampal tissue slices were blocked either by the combined administration of 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 3-((+-)-2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP) or by lowering extracellular calcium concentration ([Ca2+]o). Repetitive orthodromic activation of central neurons caused transient decrease of [Ca2+]o (measured by ion selective microelectrodes) in neuropil, attributable to influx of Ca2+ in presynaptic terminals. Presynaptic [Ca2+]o responses were rapidly and reversibly suppressed when oxygen was withdrawn from hippocampal tissue slices. The 'resting' baseline level of [Ca2+]o declined at first gradually, then precipitously as in spreading depression (SD). Presynaptic volleys during high frequency train stimulation were also depressed somewhat before SD began. We conclude that (1) presynaptic Ca2+ currents fail during hypoxia, perhaps because 'resting' intracellular free Ca2+ activity is increased and, in part, also because of partial failure of presynaptic impulse conduction; (2) the influx of Ca2+ into brain cells in hypoxic spreading depression is not mediated by glutamate/aspartate dependent channels. 相似文献
87.
对16例垂体腺瘤采用单侧鼻前庭切口经蝶切除,效果满意,既可减少手术创伤,又缩短了手术距离,且避免了美容缺陷,是一种设计巧妙,较为实用的手术方法,尤其适用于生长激素腺瘤。 相似文献
88.
The methanol extract of Cinnamomi Cortex showed antibacterial action against cariogenic bacterium,Streptococcus mutans OMZ 176. The active principle of the extract was identified to betrans-cinnamaldehyde, which was bactericidal in the minimal inhibitory concentration (MIC) of 100 μg/ml againt the strain. From the results of antibacterial activity of cinnamaldehyde and its derivatives, the acrolein group in the cinnamal-dehyde was elucidated to be an essential element for the activity. 相似文献
89.
为给临床心脏术后监测心淋巴管损伤程度及可能出现的并发症提供参考指标,以手术方法阻断羊心淋巴流并对其血清相关成份进行了测定。实验发现,实验组术后谷草转氨酶(SGOT)、谷丙转氨酶(SGPT)、碱性磷酸酶(AKP)、乳酸脱氢酶(LDH)均有不同程度的增高,以SGOT增高最为明显,术前均值为47.53U,术后2天增至104.20U,高峰出现时间最早,多在术后24小时。血清离子改变中低钾最为突出,血钾在术后2天明显降低(P<0.01),术后7天逐渐恢复,术后14天恢复至术前水平。血清蛋白改变以球蛋白降低、白蛋白/球蛋白比值升高为主。提示心淋巴循环郁滞可导致心肌细胞损伤、毛细血管通透性和结构的改变。不同酶活性的变化对郁滞的敏感度存在着差异。 相似文献
90.