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排序方式: 共有911条查询结果,搜索用时 15 毫秒
901.
Pluripotent steroidogenesis and ultrastructure in adrenocortical adenomas causing Cushing's syndrome
Adrenal vein catheterization data from 2 patients with adrenocortical adenomas causing Cushing's syndrome are presented and the electron-microscopic features of one of the tumors are described. Based on the catheterization data both tumors produced all three classes of adrenal steroids (mineralocorticoids, glucocorticoids and sex steroids). Electron-microscopic examination of the tumor cells suggested an origin from the zona fasciculata. If one accepts the theory of a common cellular origin of adrenal tumors, then the pattern of steroidogenesis would indicate that the postulated original 'stem' cell retains the potential of secreting all classes of adrenocortical steroids. The clinical presentation of such tumors would thus reflect the hypersecretion of one of the steroid classes relative to the others. 相似文献
902.
903.
Laura A. Elenich D. Nandi A. Elizabeth Kent T. Scott McCluskey M. Cruz Mohan N. Iyer Elaine C. Woodward Christopher W. Conn Amber L. Ochoa David B. Ginsburg J. J. Monaco 《Immunogenetics》1999,49(10):835-842
The proteasome is a large multicatalytic proteinase that plays a role in the generation of peptides for presentation by major
histocompatibility complex class I molecules. The 20S proteolytic core of mammalian proteasomes is assembled from a group
of 17 protein subunits that generate a distinctive pattern of spots upon two-dimensional gel electrophoresis. The genes for
most of these subunits have been cloned from humans and rats. We isolated cDNA clones for the mouse orthologues of ten of
the subunits [PSMA1 (C2), PSMA2 (C3), PSMA3 (C8), PSMA4 (C9), PSMA5 (ZETA), PSMA6 (IOTA), PSMA7 (C6-I), PSMB2 (C7-I), PSMB3
(C10-II), and PSMB5 (X)] to complete the cloning of all of the mouse subunits. Using antisera raised against these subunits
or their orthologues, we verified the identity of these proteins by two-dimensional NEPHGE-PAGE.
Received: 8 March 1999 / Accepted: 8 April 1999 相似文献
904.
David Kessel W.Barkley Butler Vaidyanathan K. Iyer Jerome P. Horwitz 《Biochemical and biophysical research communications》1982,109(1):45-48
An estrogen-bridged adenine derivative was equitoxic to both the P388 murine leukemia and an adriamycin-resistant subline, . The drug rapidly altered several P388 and membrane properties resulting in impaired nucleoside transport and increased membrane hydrophobicity. Resistance to anthracyclines in is associated with an operational barrier to drug retention which was reversed by exposure to the estrogen-bridged adenine derivative. These results suggest further exploration of the estrogen-bridged purines as chemotherapeutic agents. 相似文献
905.
906.
K S Hurkadli J K Shahid T D Nandedkar S D Mahale K S Iyer A R Sheth 《Indian journal of experimental biology》1991,29(10):897-899
A synthetic nonapeptide, which is C-terminal sequence of 94-amino acid of prostatic inhibin peptide was tested for progesterone and estrogen secretion by mouse granulosa cell cultures. Nonapeptide suppressed the progesterone and estrogen synthesis, the magnitude of suppression was highest at 5 ng dose level for progesterone and 50 ng dose level for estradiol. The study suggests that, nonapeptide exerts its effect by impairing the binding of FSH to granulosa cell receptors. 相似文献
907.
Summary This study was concerned with properties of mycelia-agglutinated terminal root clusters, or mycoplasts,' of naturally reproduced seedlings ofPinus resinosa andPinus strobus. These rhizospheric root appendages, formed at the expense of the host plant's carbohydrates, exhibited high catalytic potential, cation exchange capacity, and content of exchangeable bases, including complexible cations. These attributes suggest that mycelial clusters are important components of tree-fungus symbiotic mechanism that increase availability of nutrients to the trees. The mycelial clusters apparently perform the function of mycorrhizal short roots which are often nonexistent under the conditions of reduced radiation in well-stocked forest stands.Research supported by the College of Agriculture and Life Sciences, University of Wisconsin, Madison, and the Wisconsin Department of Natural Resources. 相似文献
908.
Marlissa A. Campbell Mari S. Golub Poorni Iyer Farla L. Kaufman Ling-Hong Li Francisco Moran Messen James E. Morgan James M. Donald 《Birth defects research. Part B, Developmental and reproductive toxicology》2009,86(3):157-175
In developmental and reproductive toxicity studies, drinking water is a common means of delivering the test agent. Reduced consumption of toxicant-containing water raises questions about indirect effects of reduced maternal fluid consumption resulting from unpalatability, versus direct effects of the test compound. Issues to consider include: objective assessment of dehydration and thirst, the relative contributions of innate and learned behaviors to drinking behavior and flavor preference, and the objective assessment of physiologic stress. Not only do lab animals under ad lib conditions consume more water than the minimum required to maintain fluid balance, animals faced with water restriction have substantial physiologic capacity for protection of metabolic processes. Measures of blood biochemistry can provide quantifiable, objective indications of fluid balance, but changes in these parameters could result from other causes such as effects of a test toxicant. Consummatory behaviors in response to perceived need are highly influenced by learning. Hence, the drinking behavior, water intake, and flavor acceptance/preference of animals used in toxicology experiments could be subject to learning experiences with the test compound. Physiological symptoms of stress produced by water deprivation may be distinguishable from the symptoms associated with other generalized stressors, such as food deprivation, but doing so may be beyond the scope of most developmental or reproductive toxicity studies. Use of concurrent controls, paired to test groups for water consumption, could help distinguish between the direct effects of a test toxicant as opposed to effects of reduced water consumption alone. Birth Defects Res (Part B), 86:157–175, 2009. ©2009 Wiley-Liss, Inc. 相似文献
909.
R D Kalraiya S S Iyer A Chati N G Mehta 《Indian journal of biochemistry & biophysics》1990,27(6):460-463
A not well-appreciated but clinically important aspect of malignant tumours is their effects on distantly located host cells. The effects, termed paraneoplastic syndromes, also pose an intriguing mechanistic problem: how do malignant cells influence properties of host cells not in contact with them? Erythrocytes from the circulation of rats bearing intraperitoneal Yoshida ascites sarcoma exhibit higher agglutinability with concanavalin A (Con A) than the cells from normal animals. Since the tumour and the red cells are not in contact, the enhanced agglutinability of the latter is a paraneoplastic effect. The mechanism by which the tumour brings about this effect is investigated as a model for paraneoplastic syndromes. The cell-free ascites fluid is able to impart high agglutinability on cells from normal animals in vitro. Also, when injected intraperitoneally in normal animals, the ascites fluid is able to enhance the agglutinability of erythrocytes in circulation. Apparently the tumour produces a substance(s) that appears in the ascites fluid and is able to diffuse into circulation, explaining the mechanism by which it can reach distant sites. From the cell-free ascites fluid three fractions have been isolated that are active in vitro. Of these, only one showed activity in vivo. From this fraction, a glycoprotein has been purified to homogeneity that confers maximal Con A-agglutinability on normal erythrocytes at 8 x 10(-7)M, at which concentration 6,400 molecules bind per cell. The protein has a molecular weight of 600 kDa in the native state and a pI of 5.35. It is made up of 4 identical subunits of Mr 170,000. It is detected in the plasma of tumour-bearing but not normal rats.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
910.
Usha Natraj K. S. N. Iyer Vijaya Raghavan Smita Mahale Jacintha Pereira 《Journal of biosciences》1990,15(4):341-350
The antigenecity of tryptic fragments of reduced and carboxymethylated chicken riboflavin carrier protein were studied. The
tryptic sites of the native riboflavin carrier protein bound to riboflavin were inaccessible. The molecular weight and the
elution profile on high performance liquid chromatography (TSK 545 DEAE) were unaltered at an enzyme to substrate ratio of
1:31. However, carboxymethylated riboflavin carrier protein could be cleaved into 3 or 4 fragments at an enzyme to substrate
ratio of 1:250 or 1:125. Chromatographic separation of the tryptic fragments on high pressure liquid chromatography (TSK 545
DEAE) revealed the presence of two fragments with different elution profiles but similar molecular weight 26 ±2 kDa. Only
one fragment (associated with peak 2) had the ability to displace chicken riboflavin carrier protein in an homologous chicken
riboflavin carrier protein radioimmunoassay. Thus, carboxymethylated ribotlavin carrier protein which does not compete with
chicken riboflavin carrier protein in the radioimmunoassay, on mild trypsinization generates a fragment which interacts with
chicken riboflavin carrier protein in radioimmunoassay. 相似文献