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排序方式: 共有498条查询结果,搜索用时 31 毫秒
491.
As a prevalent potentially life-threatening condition, abdominal aortic aneurysm (AAA) presents increasing risk of rupture as its diameter grows. However, rapid progression and rupture may occasionally occur in smaller AAAs. Earlier surgery for patients with high risk of disease progression may improve the outcome. Therefore, more precise indicators for invasive treatment in addition to diameter and abdominal symptoms are demanded. This systematic review aimed to identify potential circulating biomarkers that may predict growth rate of AAA. Cochrane and PubMed library were searched (until August 2020) for researches which reported circulating biomarkers associated with AAA expansion, and 25 papers were included. Twenty-eight identified biomarkers were further classified into five categories (inflammation and oxidative stress, matrix degradation, hematology and lipid metabolism, thrombosis and fibrinolysis, and others), and discussed further with their correlation and regression analysis results. Larger prospective trials are required to establish and evaluate prognostic models with highest values with these markers. 相似文献
492.
J. M. Drummond D. L. Macmillan 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,183(5):603-619
Two opposing muscle systems underlie abdominal contractions during escape swimming in crayfish. In this study we used extracellular
and intracellular stimulation, recording and dye-filling to systematically identify each of the five deep extensor excitors
and single inhibitor of the crayfish, Cherax destructor. Functional associations of each neuron were characterised by recording its responses to sensory and abdominal cord inputs,
its extensor muscle innervation pattern, and its relationships with other neurons. Each excitor receives excitatory input
from the tonic abdominal stretch receptors and the largest neuron also receives input from the phasic stretch receptor. The
two largest excitors innervate the muscle bundle containing the fastest fibres and may be electronically coupled. The smaller
neurons may also be electronically coupled and innervate the remaining deep extensor fibres which display dynamic characteristics
from fast to medium-fast. The inhibitor does not receive input from the stretch receptors, but is strongly excited by tactile
afferents. The implications of these findings for the current models of the control of abdominal tailflips and swimming are
discussed.
Accepted: 21 June 1998 相似文献
493.
M.C. Horn M. Breton E. Deudon E. Berrou J. Picard 《Biochimica et Biophysica Acta (BBA)/General Subjects》1983,755(1):95-105
Aortic proteoglycans, from the growth medium of cultured smooth muscle cells and from sequential associative and dissociative extracts of the tissue of origin, the pig aorta, were isolated and purified by precipitation with cetylpiridinium chloride. After isopycnic CsCl gradient centrifugation under associative conditions 94% of the cell-secreted proteoglycans were recuperated in the bottom one fifth (?av = 1.62 g/ml) fraction. In contrast 80% of the tissue proteoglycans of both extracts, fractionated into two fractions: the bottom one fifth (?av = 1.60 g/ml) fraction and three fifths (?av = 1.42 g/ml) fraction. Fractionated tissue proteoglycans were composed predominantly of chondroitin sulfate-dermatan sulfate (83–90%) with lower proportions of heparan sulfate (5–11%) and hyaluronic acid (3–6%) whilst cell-secreted proteoglycans showed a similar glycosaminoglycan composition but with a higher proportion of hyaluronic acid (11–13%). Sepharose 2B and C1-2B chromatography of tissue proteoglycans of high buoyant density showed the presence of only subunit proteoglycans whilst those of intermediate density contained a complex species, partially dissociable in 4 M guanidinium chloride, along with Kav 0.50 subunit species. The latter was also observed for cell-secreted proteoglycans although obtained at high buoyant density. The cell-secreted subunit proteoglycans became separated into two distinct populations when chromatographed on Sepharose 4B and C1-4B, half of which eluted in the column Vo and the rest at a Kav of 0.34.. The majority of subunit macromolecules eluted at the Vo fractions of Sepharose 6B and C1-6B columns. Unlike the major species of cartilage proteoglycans, only approx. 20% of purified arterial proteoglycans formed complexes. This proportion could be increased by only 4–7% by interaction, of a mixture of subunit cell-secreted and tissue-extracted proteoglycans, with hyaluronic acid. These results suggest that proteoglycans secreted by cultured aortic smooth muscle cells and present in the aortic tissue possess certain similar physicochemical properties and are present in the form of complex and several subunit species. 相似文献
494.
Victor Plourde Helen C. Wong John H. Walsh Helen E. Raybould Yvette Tach 《Peptides》1993,14(6):1225-1229
The role of capsaicin-sensitive pathways and CGRP in postoperative gastric ileus was investigated. Abdominal surgery was performed under enflurane anesthesia, and 5 min later, the 20-min rate of gastric emptying was measured by the phenol red method in conscious rats. Surgery inhibited gastric emptying by 76–83% compared with rats receiving anesthesia alone. Capsaicin on the celiac/mesenteric ganglia (10–21 days before) reduced gastric ileus by 33 ± 8%, whereas perivagal capsaicin had no effect. The IV CGRP-induced inhibition of gastric emptying was completely reversed by the CGRP antagonist, CGRP(8–37) (30 μg, IV); CGRP(8–37) (15, 30, or 60 μg) or CGRP monoclonal antibody #4901 (2 mg protein) decreased the inhibition of gastric emptying by 11 ± 7%, 51 ± 13%, 47 ± 3%, and 45 ± 17%, respectively. These results indicate that CGRP and splanchnic capsaicin-sensitive afferents are involved in mediating part of the gastric ileus observed immediately after abdominal surgery. 相似文献
495.
496.
Lily Lee Salcedo Carl Franzblau 《In vitro cellular & developmental biology. Plant》1981,17(2):114-120
Summary This study describes the ability of aortic smooth muscle cells to synthesize and accumulate collagen with time in culture.
Inasmuch as smooth muscle cell cultures multilayer and continue to divide, albeit slowly, and can be maintained in the same
vessels where seeded for extended periods of time, a long-term aging study from a single subcultivated population of cells
was carried out. This is different from the usual cell-culture aging achieved by an increase in cell population doublings
obtained by repeated subcultivations. The latter process, which is trypsin induced, involves a changing cellular environment
including the extracellular matrix that is produced by the cells in culture.
Second subcultures of weanling rabbit, aortic media, smooth muscle cells maintained for different periods of time up to 14
wk displayed decreasing hydroxyproline formation with time. Proline hydroxylation was determined by pulsing these second-passage
cells with [14C]proline for 24 h at various times during the 14 wk period. The cell layer and medium were evaluated separately for radioactive
proline and hydroxyproline and the medium for bacterial collagenase-susceptible protein as well. The percent of hydroxylation
in the medium decreased from >31% within 1 wk after plating to 15.2% after 14 wk in culture. The percent of collagenase-susceptible
protein in the medium decreased in a comparable manner. The DNA levels increased during the entire period although initially
somewhat more rapidly. Accumulation of protein in the extracellular matrix continued during the 14-wk span. The accumulation
of hydroxyproline in the extracellular matrix also continued to increase throughout the culture period, but it did slow down
significantly. Yet the cells appear not to have lost their ability to accumulate connective tissue and protein in the insoluble
cell layer. The data suggest clearly that the percent collagen synthesis relative to total protein synthesis decreases in
the older cultures; total protein synthesis also decreases as expected.
This study was supported by NIH Program Projects AG00001 and HL 13262. 相似文献
497.
498.