全文获取类型
收费全文 | 11452篇 |
免费 | 748篇 |
国内免费 | 349篇 |
专业分类
耳鼻咽喉 | 36篇 |
儿科学 | 45篇 |
妇产科学 | 39篇 |
基础医学 | 1403篇 |
口腔科学 | 719篇 |
临床医学 | 656篇 |
内科学 | 2543篇 |
皮肤病学 | 121篇 |
神经病学 | 401篇 |
特种医学 | 167篇 |
外国民族医学 | 1篇 |
外科学 | 633篇 |
综合类 | 1256篇 |
预防医学 | 533篇 |
眼科学 | 69篇 |
药学 | 2057篇 |
7篇 | |
中国医学 | 1766篇 |
肿瘤学 | 97篇 |
出版年
2024年 | 51篇 |
2023年 | 210篇 |
2022年 | 1200篇 |
2021年 | 1243篇 |
2020年 | 436篇 |
2019年 | 343篇 |
2018年 | 360篇 |
2017年 | 391篇 |
2016年 | 369篇 |
2015年 | 409篇 |
2014年 | 758篇 |
2013年 | 912篇 |
2012年 | 593篇 |
2011年 | 667篇 |
2010年 | 430篇 |
2009年 | 431篇 |
2008年 | 393篇 |
2007年 | 373篇 |
2006年 | 365篇 |
2005年 | 288篇 |
2004年 | 255篇 |
2003年 | 246篇 |
2002年 | 215篇 |
2001年 | 183篇 |
2000年 | 135篇 |
1999年 | 116篇 |
1998年 | 112篇 |
1997年 | 95篇 |
1996年 | 108篇 |
1995年 | 85篇 |
1994年 | 79篇 |
1993年 | 65篇 |
1992年 | 72篇 |
1991年 | 49篇 |
1990年 | 52篇 |
1989年 | 55篇 |
1988年 | 38篇 |
1987年 | 38篇 |
1986年 | 38篇 |
1985年 | 44篇 |
1984年 | 36篇 |
1983年 | 40篇 |
1982年 | 47篇 |
1981年 | 24篇 |
1980年 | 20篇 |
1979年 | 14篇 |
1978年 | 20篇 |
1977年 | 7篇 |
1976年 | 17篇 |
1975年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
BACKGROUND/PURPOSE: Sensitive skin is a condition associated with reduced tolerance to environmental factors and/or the application of topical products, such as cosmetics. Its pathophysiology has not been fully elucidated and few data are available on its prevalence. The aim of this study was to investigate possible correlation between objective sensitivity and skin surface microrelief. METHODS: During an epidemiological survey conducted for a campaign promoted by International Society of Plastic Dermatology in Italy, 243 adult healthy subjects of both sexes with no evident dermatological disorder but positive to the lactic acid stinging test, were submitted to cyanoacrylate stratum corneum stripping from the volar forearm for the determination of the irregularity of the skin surface microrelief (irregularity skin index (ISI)). RESULTS: A significant correlation was found between intensity of symptoms in stingers and ISI (r(s)=-0.47; P<0.001). CONCLUSION: Sensitive skin is common in the healthy population. ISI can contribute towards the identification of subjects with sensitive skin and the development of more specific skin treatments for this prevalent condition. 相似文献
2.
M. NEUBRAND I. GREINWALD H. LOBENTANZER G. PAUMGARTNER H. HERMEKING T. SAUERBRUCH 《European journal of clinical investigation》1997,27(3):234-241
Efficient fragmentation is the most important prerequisite for successful treatment of gallstones by extracorporeally induced shock waves. No data are available on the amount of energy necessary for stone disintegration and on the threshold energy below which no further fragmentation occurs. We therefore performed an in vitro investigation on human cholesterol gallstones to elucidate physical laws governing shock-wave lithotripsy. First, the focal pressure of the lithotripter was measured to calculate the energy traversing a stone. Second, 96 gallstones from 16 gall bladders were analysed with respect to physicochemical composition, radiological features and ultrasound before fragmentation was performed. Energy for stone disintegration was constant within each stone family but varied between 4.6 J mL?1 and 36.8 J mL?1 in different families. This energy correlated linearly with stone volume. None of the radiological and physicochemical factors revealed a clear-cut correlation of the different energies necessary for similar stone disintegration. The threshold energy differed between 0.26 mJ and 1.04 mJ per pulse. In conclusion, stone volume was the best parameter predicting stone fragmentation. However, in cholesterol stones with a similar composition the required energy per volume varies considerably together with the threshold energy. Radiological and ultrasound parameters appear to be of minor importance in explaining these differences. 相似文献
3.
Chakraborty Bhaswat S. Sardessai Manik S. Jaworski Theodore J. Midha Kamal K. Hawes Edward M. 《Pharmaceutical research》1987,4(3):207-213
For the separate development of radioimmunoassay procedures for thioridazine and its two major active metabolites, mesoridazine and sulforidazine, three haptens, respectively, 2-methylthio-, 2-methylsulfinyl-, and 2-methylsulfonyl-substituted 10-[2-[l-(2-carboxyethyl)-2-piperidinyl]ethyl]-10H-phenothiazine, were synthesized and characterized. Thioridazine hapten was coupled to bovine serum albumin, whereas the haptens for mesoridazine and sulforidazine were coupled to porcine thyroglobulin. The number of hapten residues per mole of carrier protein was determined in each case by an ultraviolet spectrophotometric method. Polyclonal antibodies to each hapten–protein conjugate were obtained in rabbits, and titers of the antisera were checked by evaluating their binding characteristics to the appropriate tritiated analyte. A hapten for the ring sulfoxide metabolite of thioridazine was also synthesized. 相似文献
4.
目的观察补脾泻肝法治疗腹泻型肠易激综合征的临床疗效。方法100例腹泻型肠易激综合征患者随机分为2组,治疗组60例给予白术芍药散加味,对照组40例给予丙咪嗪合替加色罗治疗。2组均4周为1个疗程,观察疗效,并于3-6个月后观察2组病例复发情况。结果治疗组治愈率为65%,总有效率为85%,6个月内复发率为20%,对照组则分别为32.5%、72.5%、55.56%,2组比较差异均有统计学意义(均P<0.05)。结论补脾泻肝法治疗腹泻型肠易激综合征优于丙咪嗪合替加色罗,疗效确切。 相似文献
5.
Simultaneous Quantification of an Enantiomer and the Racemic Compound of Ibuprofen by X-ray Powder Diffractometry 总被引:1,自引:0,他引:1
Purpose. An X-ray powder diffractometric method was developed for the simultaneous quantification of the relative amounts of the racemic compound (±) of ibuprofen (I) and S(+)-ibuprofen (II), when they occur as a mixture.
Methods. The X-ray powder diffraction patterns of I and II show pronounced differences. This formed the basis for the determination of the relative amounts of I and II when they occur as a mixture. X-ray lines with d-spacings of 14.41 and 4.37 Å were unique to I and II, respectively. Mixtures containing different proportions of I and II were prepared which also contained lithium fluoride (III) as an internal standard.
Results. A linear relationship was obtained when the intensity ratio (intensity of the 4.37 Å line of II/intensity of the 2.01 Å line of III) was plotted as a function of the weight fraction of II in the mixture. Similar results were obtained in the case of I. Using these standard curves, the weight fractions of I and II in 'unknown' mixtures were determined. The experimentally determined analyte concentration ranged between 98 and 104% of the true value. The relative error in the analyses of individual samples was < 10%. The minimum detectable weight fraction of I in II and II in I were 0.032 (3.2% w/w) and 0.034 (3.4% w/w), respectively. The minimum quantifiable weight fractions were 0.136 for I and 0.112 for II. Since the X-ray diffraction patterns of S(+)-ibuprofen and R(–)-ibuprofen are identical, the conclusions drawn regarding mixtures of I and II will also hold true in the quantitative analyses of mixtures of I and R(–)-ibuprofen. 相似文献
6.
Akosua N.J.A. de Groot Pieter W.J. van Dongen Tom B. Vree Tom K.A.B. Eskes 《European journal of obstetrics, gynecology, and reproductive biology》1995,60(2):101-107
Objective: To study the pharmacodynamic and pharmacokinetic properties of oral and intravenous methylergometrine upon uterine motility during menstruation. Study-design: Intra-uterine pressure was measured in six volunteers with a fluid-filled sponge-tipped catheter during menstruation. Methylergometrine was given orally (0.5 mg) or intravenously (0.2 mg) in a cross-over design. Results: After intravenous administration, a fast increase of the frequency of uterine contractions and basal tone occurred with a decrease of amplitude, lasting at least 30 min. Oral administration had a late and less marked effect on uterine motility. An intravenous dose administered 24 h after an oral dose had no effect on uterine motility. Pharmacokinetic data, such as the maximum plasma concentration (Cmax), the time at which Cmax is reached (tmax) and the half-life of absorption (t1/2abs) also demonstrated large individual variations after oral administration. Conclusion: Oral administration of methylergometrine had an unpredictable and late effect on uterine motility on the menstruating uterus, probably due to an unpredictable bioavailability, in contrast with the fast and predictable effect after intravenous administration. 相似文献
7.
8.
强化婴幼儿奶粉中叶酸的测定 总被引:1,自引:0,他引:1
强化叶酸的奶粉在0.05M K_2HPO_4缓冲液中,经均质,调pH4.5,15000g离心20分钟,其清液调pH4.0,进行CGS树脂离子交换层析,用10ml KClK_2HPO_4洗脱,调pH7.0,进行HPLC测定,采用300x3.9mm ODS反相柱,移动相0.05M K_2HPO+MeOH(91+9),流速1ml/分,紫外检测器波长285nm,灵敏度0.0050D。方法相对标准偏差为±3.3%,回收率为87%,最小检测量为0.02μg/ml。 相似文献
9.
10.
热力学计算表明,H2,N2的过量有助于提高TiN的产率,但能耗也相应增加。为此考察了温度,流量,TiCl4携带量,混合方式对产物性能的影响。结果表明,流量增加,温度升高,TiCl4携带量增加,混合愈好,则产物粒径愈小。在此基础上采用微波等离子体化学气相沉积法,合成了粒径为123-284nm的TiN超细颗粒 相似文献