全文获取类型
收费全文 | 1261篇 |
免费 | 78篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 120篇 |
儿科学 | 17篇 |
妇产科学 | 13篇 |
基础医学 | 172篇 |
口腔科学 | 46篇 |
临床医学 | 119篇 |
内科学 | 246篇 |
皮肤病学 | 36篇 |
神经病学 | 102篇 |
特种医学 | 72篇 |
外科学 | 106篇 |
综合类 | 21篇 |
一般理论 | 1篇 |
预防医学 | 54篇 |
眼科学 | 92篇 |
药学 | 93篇 |
肿瘤学 | 75篇 |
出版年
2023年 | 6篇 |
2022年 | 16篇 |
2021年 | 37篇 |
2020年 | 20篇 |
2019年 | 29篇 |
2018年 | 37篇 |
2017年 | 21篇 |
2016年 | 27篇 |
2015年 | 36篇 |
2014年 | 39篇 |
2013年 | 47篇 |
2012年 | 72篇 |
2011年 | 68篇 |
2010年 | 60篇 |
2009年 | 33篇 |
2008年 | 48篇 |
2007年 | 78篇 |
2006年 | 46篇 |
2005年 | 55篇 |
2004年 | 41篇 |
2003年 | 44篇 |
2002年 | 39篇 |
2001年 | 30篇 |
2000年 | 41篇 |
1999年 | 32篇 |
1998年 | 23篇 |
1997年 | 24篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 16篇 |
1991年 | 23篇 |
1990年 | 24篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 14篇 |
1978年 | 6篇 |
1976年 | 8篇 |
1974年 | 6篇 |
1969年 | 5篇 |
1957年 | 5篇 |
排序方式: 共有1385条查询结果,搜索用时 15 毫秒
1.
Miguel A. Sanz Pau Montesinos Haesook T. Kim Guillermo J. Ruiz-Argüelles María S. Undurraga María R. Uriarte Lem Martínez Rafael H. Jacomo Homero Gutiérrez-Aguirre Raul A. M. Melo Rosane Bittencourt Ricardo Pasquini Katia Pagnano Evandro M. Fagundes Edo Vellenga Alexandra Holowiecka Ana J. González-Huerta Pascual Fernández Javier De la Serna Salut Brunet Elena De Lisa José González-Campos José M. Ribera Isabel Krsnik Arnold Ganser Nancy Berliner Raul C. Ribeiro Francesco Lo-Coco Bob L?wenberg Eduardo M. Rego 《Annals of hematology》2015,94(8):1347-1356
2.
3.
Regional lens adenine nucleotide levels were determined in human and bovine lenses using sensitive HPLC techniques. In adult lenses of both species adenine nucleotide levels were highest in the anterior cortex (plus epithelium and capsule) followed by the posterior cortex (plus capsule) and lowest in the nucleus. With increasing lens age ATP level remained steady in the anterior cortex (plus epithelium and capsule) and nucleus, while those in the posterior cortex showed a tendency toward decrease. In both species, human as well as bovine, adenine nucleotide levels of the anterior cortex (plus epithelium and capsule) underwent early postmortem changes. Thus, immediate postmortem sampling as well as regional determinations are a must for detailed studies of lens nucleotide metabolism. 相似文献
4.
Multiclefted nuclei. A helpful feature for identification of intermediate trophoblastic cells in uterine curetting specimens. 总被引:1,自引:0,他引:1
Intermediate trophoblast is a distinct form of trophoblast, the presence of which in uterine curettings is considered a reliable indicator of intrauterine pregnancy even in the absence of chorionic villi. However, the appearance of intermediate trophoblastic cells have not been described in sufficiently specific terms to permit their reliable identification, and distinction from decidual cells can be difficult. We have noticed for some time that the intermediate trophoblastic cells often show multiple deep clefts in the nuclei, and the present study was performed to address the issue of whether this nuclear feature is reliable for their identification. We reviewed 242 uterine curettings of intrauterine pregnancy, documented by the presence of chorionic villi, and were able to find a distinct population of cells with large, hyperchromatic, multiclefted nuclei scattered in the decidua in 88% of the cases. In most instances, these cells produced a characteristic variegated pattern that was readily recognizable at low magnification. Positive immunostaining for cytokeratin (CAM 5.2) in these isolated cells within the decidua confirmed their trophoblastic nature. In contrast, multiclefted nuclei were absent in the 51 negative control cases, which included decidualized endocervical polyps (40 cases), uterine curettings from patients with tubal pregnancy (10 cases), and endometriosis with decidual change (one case). We conclude that intermediate trophoblastic cells can usually be reliably identified in curettings of intrauterine pregnancy by their characteristic nuclear multiclefting. 相似文献
5.
Spleen cells of a Biozzi HR mouse immunized with a bovine serum albumin-methotrexate conjugate were fused with P3-X63-Ag8.653 mouse myeloma cells. Twenty-three monoclonal antibodies (MAbs), selected by indirect ELISA, were produced and partially characterized. Using methotrexate (MTX) and eight structurally related compounds, binding specificities of the MAbs were assessed by inhibition enzyme immunoassay. All the MAbs had very low affinity for folic acid and its analogs and for the major MTX metabolite 7-hydroxymethotrexate. Using a computer cluster analysis program based on the binding specificities, the MAbs were divided into three groups. The thirteen MAbs in group I recognized primarily the pteridine portion of the MTX molecule; the eight group II MAbs recognized the benzene ring as well as the pteridine structure. The two MAbs in group III poorly distinguished between the different parts of the MTX molecule. The apparent equilibrium association constants of the anti-MTX MAbs in groups I, II, and III ranged from 7 x 10(9) to 3 x 10(8) M-1 (except for 1 MAb), from 5 x 10(7) to 6 x 10(6) M-1 (except for 2 MAbs), and from 1 x 10(6) to 3.5 x 10(5) M-1, respectively. 相似文献
6.
H Pau 《Klinische Monatsbl?tter für Augenheilkunde》1988,193(6):550-553
The three important types of age-related senile cataract, namely deep supranuclear cortical cataract, superficial subcapsular cortical cataract (sometimes associated with secondary nuclear cataract), and primary nuclear cataract, are arranged in a table which may be used for quick reference with regard to clinical features - slit lamp findings, age at onset of opacification, rate of progression, and related biochemistry (e.g., ATP content, glutathione content, and the cation pump (K+ greater than Na+] - as well as etiological features. The significance of the table is illustrated on the basis of an important example from the literature ("Sunlight and Human Cataracts"). 相似文献
7.
Purified 60-kilodalton Legionella protein antigen with Legionella-specific and nonspecific epitopes. 总被引:9,自引:4,他引:9
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
B B Plikaytis G M Carlone C P Pau H W Wilkinson 《Journal of clinical microbiology》1987,25(11):2080-2084
In a previous study, all convalescent-phase sera from patients with culture-confirmed legionellosis reacted on immunoblots with a Legionella genus-wide 58-kilodalton (kDa) protein antigen (J.S. Sampson, B.B. Plikaytis, and H.W. Wilkinson, J. Clin. Microbiol. 23:92-99, 1986). The present study was done to immunologically characterize and determine the diagnostic relevance of this purified antigen. The antigen was precipitated from enriched cell extracts with ammonium sulfate and purified by high-pressure liquid chromatography. High-titered rabbit antiserum produced to the purified protein was used to show its presence on immunoblots in the 60-kDa range in 38 Legionella serogroups, representing 23 species, and in 39 non-Legionella bacteria. The antiserum was made specific for Legionella strains by sequential absorptions with Bordetella pertussis, Pseudomonas aeruginosa, and Pseudomonas fluorescens whole cells. Serum from legionellosis patients reacted with both specific and nonspecific epitopes. Results of indirect immunofluorescence experiments showed that neither specific nor nonspecific epitopes of the 60-kDa protein were surface exposed on Legionella cells and that cross-reactive epitopes were variably exposed on non-Legionella bacteria. The 60-kDa protein antigen should be useful in diagnostic tests for legionellosis if care is taken to expose cryptic epitopes and if the tests use or measure only the Legionella-specific epitopes. 相似文献
8.
Calcium ionophore-induced acrosome reaction correlates with fertilization rates in vitro in patients with teratozoospermic semen 总被引:5,自引:3,他引:5
The aim of this study was to determine the relationship between calcium
ionophore A23187-induced acrosome reaction (AR) and sperm fertilizing
ability. Semen samples remaining after preparation for standard IVF were
studied in 109 patients who had sperm concentrations > or =20 x
10(6)/ml. Ionophore-induced AR was performed on motile spermatozoa selected
by centrifugation on a Percoll gradient. Semen analysis was performed using
standard methods. Patients with higher (>50%, n = 76) fertilization
rates had significantly higher ionophore-induced AR than patients with
lower (<50%, n = 33) fertilization rates (49 +/- 14 versus 38 +/- 21%, P
< 0.05). When the data from all patients were analysed by logistic
regression, only the percentage sperm motility in insemination medium and
ionophore-induced AR were significantly related to fertilization rates.
Similar results were also obtained when the data from a subgroup of
patients with poor (<15% normal) sperm morphology were analysed.
However, when patients with normal sperm morphology > or =15% were
analysed separately, only sperm count and the percentage of spermatozoa
with progressive motility in semen were significantly related to
fertilization rates. In conclusion, ionophore- induced AR was significantly
related to fertilization rates in vitro mainly in patients with
teratozoospermic semen. Tests for ionophore- induced AR may provide
additional information about sperm fertilizing ability but may not indicate
specific defects of the physiological AR.
相似文献
9.
Detection of reactive oxygen species (ROS) and apoptosis in human fragmented embryos 总被引:8,自引:2,他引:8
Yang HW; Hwang KJ; Kwon HC; Kim HS; Choi KW; Oh KS 《Human reproduction (Oxford, England)》1998,13(4):998-1002
In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture
environment differs from in-vivo conditions in that the oxygen
concentration is higher, and in such conditions the mouse embryos show a
higher concentration of reactive oxygen species (ROS) in simple culture
media. ROS are believed to cause damage to cell membranes and DNA
fragmentation in somatic cells. This study was conducted to ascertain the
level of H2O2 concentration within embryos and the morphological features
of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31
fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was
obtained from the IVF-embryo transfer programme. The relative intensity of
H2O2 concentrations within embryos was measured using
2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence
imaging and DNA fragmentation was observed with transmission electron
microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations
were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/-
SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and
unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed
only in fragmented embryos, and was absent in non-fragmented embryos.
Electron microscopic findings confirmed apoptotic bodies and cytoplasmic
condensation in the fragmented blastomeres. We conclude that there is a
direct relationship between increased H2O2 concentration and apoptosis, and
that further studies should be undertaken to confirm these findings.
相似文献
10.
Stein TP; Oram-Smith JC; Leskiw MJ; Wallace HW; Long LC; Leonard JM 《The American journal of physiology》1976,230(5):1321-1325