全文获取类型
收费全文 | 1346篇 |
免费 | 119篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 68篇 |
妇产科学 | 43篇 |
基础医学 | 174篇 |
口腔科学 | 36篇 |
临床医学 | 125篇 |
内科学 | 238篇 |
皮肤病学 | 52篇 |
神经病学 | 54篇 |
特种医学 | 93篇 |
外科学 | 233篇 |
综合类 | 31篇 |
预防医学 | 91篇 |
眼科学 | 38篇 |
药学 | 126篇 |
中国医学 | 4篇 |
肿瘤学 | 50篇 |
出版年
2023年 | 13篇 |
2022年 | 30篇 |
2021年 | 54篇 |
2020年 | 34篇 |
2019年 | 44篇 |
2018年 | 57篇 |
2017年 | 39篇 |
2016年 | 28篇 |
2015年 | 53篇 |
2014年 | 44篇 |
2013年 | 65篇 |
2012年 | 100篇 |
2011年 | 95篇 |
2010年 | 56篇 |
2009年 | 42篇 |
2008年 | 37篇 |
2007年 | 45篇 |
2006年 | 52篇 |
2005年 | 50篇 |
2004年 | 52篇 |
2003年 | 39篇 |
2002年 | 33篇 |
2001年 | 13篇 |
2000年 | 28篇 |
1999年 | 16篇 |
1998年 | 23篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 18篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 18篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 8篇 |
1988年 | 21篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 18篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1980年 | 7篇 |
1978年 | 7篇 |
1971年 | 6篇 |
1969年 | 7篇 |
1968年 | 6篇 |
1964年 | 8篇 |
1963年 | 8篇 |
1962年 | 6篇 |
排序方式: 共有1471条查询结果,搜索用时 15 毫秒
1.
The broad background of scattered light observed in spectra of cell suspensions is reduced by factors of up to 20 by immersion refractometry allowing for improved spectroscopic determination of the absorption properties of cells in the 325-820 nm range. Refractive-index matched spectra of E. coli C1a exhibit a set of resonant features near 422, 561, and 582 nm. Exposure wavelengths are chosen based on this spectrum and cell viability is investigated in E. coli suspensions exposed to 350, 400, 422, 440, and 700 nm radiation delivered in nanosecond pulses with total doses from 500 millijoules to 60 Joules. We observe a loss in cell viability for doses greater than 1 Joule at 422 nm and for all doses at other wavelengths; exposures of less than 1 Joule at 422 nm enhance growth. Excluding exposures at wavelengths within the resonant feature, longer wavelengths are less effective at reducing the viability of E. coli C1a. This indicates the occurrence of at least two absorption processes. 相似文献
2.
Sequential contrast-enhanced MR imaging of the penis 总被引:1,自引:0,他引:1
3.
Genotype-phenotype correlation for nucleotide substitutions in the IgII- IgIII linker of FGFR2 总被引:6,自引:3,他引:3
4.
The ability of several bacterial species to adhere to human nasal mucosal cells and their distribution on nasal mucosal surfaces was studied. Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and Pseudomonas aeruginosa adhered to scraped nasal mucosal cells. In contrast, viridans streptococci and Klebsiella pneumoniae exhibited feeble or no adherence to nasal mucosal cells. S. aureus affinity for the nasal mucosal cells of carriers of S. aureus was greater than for those of the noncarriers (P less than 0.005). Heat treatment of S. aureus did not block, but slightly reduced, its binding to mucosal cells. The data suggest a high degree of specificity involved in the adherence of bacteria to nasal mucosal cells. The greater affinity of S. aureus for the nasal mucosal cells of carriers (than noncarriers) seems to be a property of mucosal cells rather than bacteria. 相似文献
5.
Protection of Chicken Embryos by Viridans Streptococci Against the Lethal Effect of Staphylococcus aureus 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Raza Aly Howard I. Maibach Henry R. Shinefield Adrian D. Mandel 《Infection and immunity》1974,9(3):559-563
Chicken embryos were used to investigate the mechanism by which viridans streptococci inhibit the growth of pathogenic staphylococci. Ten-day-old embryonated eggs were infected allantoically. At a concentration of 1.8 x 10(2) colony-forming units (CFU) of viridans streptococci, the percentage of fatalities was less than 10%. There was 80% fatality with 8 x 10(1) CFU of Staphylococcus aureus strain 502A and 100% when a 100-fold increase in concentration was used. An inoculum size of 10(2) to 10(3) CFU of viridans streptococci was chosen to protect the embryos against the lethal effect of strain 502A when challenged 24 h later. The survival after challenging at 4 days was 93% in protected eggs and 37% in unprotected eggs. Chicken embryos receiving heat-killed viridans and challenged with strain 502A when examined after 4 days did not demonstrate a protective effect. This protection of embryonated eggs could not be transferred by administration of sterile filtrate of allantoic fluid in which protecting strain was grown. The experimental infection of embryonated eggs has demonstrated that prior allantoic infection with viridans streptococci affords significant protection against subsequent challenge with virulent staphylococci. 相似文献
6.
Horne G; Jamaludin A; Critchlow JD; Falconer DA; Newman MC; Oghoetuoma J; Pease EH; Lieberman BA 《Human reproduction (Oxford, England)》1998,13(11):3045-3048
Insemination with donor spermatozoa is an integral part of infertility
treatment. For the last 3 years in our unit, intrauterine insemination with
donor spermatozoa (IUID) has been used in preference to vaginal
insemination. In this retrospective study, patients were offered an initial
course of five single intrauterine inseminations with cryopreserved donor
spermatozoa and treatment was then reviewed. A total of 389 patients
received 1465 inseminations. In all, 1119 cycles were monitored using
luteinizing hormone serum analyses and 346 cycles using the urine home test
kits. The clinical pregnancy rate per insemination for the cycles monitored
by the serum assay was 18.0% (202/1119) compared with the urine cycles
(13.7%, 46/346) (P <05). The pregnancy loss rate was not significantly
different (14.4%, 29/202 and 21.7%, 10/46) (serum and urine cycles
respectively). The viable clinical pregnancy rate was significantly higher
(P <03) for the serum cycles than for the cycles using the urinary
monitoring (15.5%, 173/1119 and 10.4%, 36/346 respectively). The cycles
monitored by serum assay had a significantly higher cumulative viable
clinical pregnancy rate (P <0001) of 70.2% after nine inseminations
compared with the urine monitored cycles of 54.8%. The majority of patients
opted for the serum cycles, with a minority self-selecting the urine cycles
mainly for travelling convenience. The explanation for the significant
differences between the viable clinical pregnancy rates per insemination
and the cumulative viable clinical pregnancy rates may be due to the
sensitivity of the urine home test kit or the patients' interpretation of
the result.
相似文献
7.
Magdy S. Aly Paola Dal Cin Herman Van Den Berghe Wim Van De Voorde Hein Van Poppel Filip Ameye Luc Baert 《Genes, chromosomes & cancer》1994,9(4):227-233
We combined conventional cytogenetic analysis and fluorescence in situ hybridization of short-term cultures of 28 samples from benign prostatic hyperplasia. Lou of the Y chromosome was the most common chromosome change, followed by trisomy 7. Trisomy 7, however, may be unrelated to the origin of benign prostate hyperplasia, in which the only and not very specific change seems to be the loss of the Y chromosome. Genes Chrom Cancer 9:227-233 (1594). © 1994 Wiley-Liss, Inc. 相似文献
8.
Paola Dal Cin Chris De Wolf-Peeters Magdy S. Aly Georges Deneffe Walter Van Mieghem Herman Van Den Berghe 《Genes, chromosomes & cancer》1993,6(4):243-244
Cytogenetic analysis of a thymoma showed the presence of a ring chromosome 6 as the sole chromosome abnormality. © 1993 Wiley-Liss, Inc. 相似文献
9.
Mahmoud Hassanein El-Saied A. Aly Yousf A. Abbas Samia M. El-Sigeny 《Macromolecular chemistry and physics.》1993,194(6):1817-1825
To overcome mass transfer limitations which are usually encountered on immobilizing active catalysts, cationic latex particles were used as support for the cobalt(II) complex of disodium N,N′-bis(salicylidene)ethylenediamine-5,5′-disulfonate ( 1 ). The cationic latex 2 was prepared by emulsion copolymerization of chloromethylstyrene (m/p-isomer mixture 60/40) and divinylbenzene (m/p-isomer mixture) followed by treatment with trimethylamine. The latexbound catalyst from 1 and 2 was found to considerably increase the reaction rate of the autoxidation of 2,6-di-tert-butylphenol in water as compared with the conventional polymer-free system. Reaction products were identified as the oxidative coupling product 3,3′,5,5′-tetra-tert-butyldiphenoquinone (3,3′,5,5′-tetra-tert-butyl-4,4′-dioxo-1,1′-bicyclohexa-2,5-dienylidene) and 2,6-di-tert-butyl-1,4-benzoquinone. All reactions showed an induction period before the start of dioxygen consumption. The rate of autoxidation in the three-phase mixtures of water, latex particles, and phenol droplets was not affected significantly by the method of mixing. The reaction rate increased as the concentration of 1 increased. Increasing the partial pressure of dioxygen in the range between 0,25 and 1,0 atm (2,53. 104 – 1,01. 105 Pa) gave a small increase in rate. The colloidal latex catalyst from 1 and 2 showed some loss of activity after successive runs. 相似文献
10.
Hernia - Patients who present with symptomatic, clinically occult, radiologically evident (SCORE) inguinal hernia represent diagnostic and therapeutic challenge with a wide differential diagnosis... 相似文献