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1.
Food availability is important to the dynamics of animal social organizations or populations. However, the role of winter
food availability in animal population dynamics is still controversial. We carried out an experimental study to test Lack’s
hypothesis that reduced food in winter limits survival and spring numbers of breeding individuals of social groups, using
the Mongolian gerbil (Meriones unguiculatus) as model species. We established 24 gerbil social groups in 24, 10 × 10 m, pens in September 2008. We provided wheat seeds
as supplemental food in 12 enclosures from September 2008 to March 2009; the other 12 enclosures, not provided with supplemental
food, served as controls. We live-trapped gerbils at a 2-week interval from September to April. Supplemental food during winter
increased biweekly survival by 10% relative to that in control groups. Only four control social groups survived to the end
of our study whereas all 12 food-supplemented social groups survived through our study period. Supplemental food also increased
cumulative numbers of recruits and group sizes of gerbils. We conclude that winter food availability limits winter survival
and spring social groups or population sizes of Mongolian gerbils. 相似文献
2.
An interspecific somatic hybrid between Actinidia chinensis and Actinidia kolomikta and its chilling tolerance 总被引:2,自引:0,他引:2
Protoplasts isolated from cotyledon-derived callus of Actinidia chinensisPlanch. var. chinensis (2N=2x=58) were fused with mesophyll protoplasts of Actiniadia kolomikta(Maxim. et Rupr.) Maxim (2N=2x=58) using a PEG method. Plantlets were regenerated from the fusion product clone 11. RAPD analyses, chromosome numbers of root tip cells and fluorescence peak position of leaf nuclei confirmed that clone 11 was an interspecific somatic hybrid (2N=4x=116) between A. chinensis and A. kolomikta. The chilling tolerance of the somatic hybrid was tested with in vitro leaves at low temperatures. Based on data of leaf thickness, electroconductivity, proline levels, malondialdehyde content and activity of superoxide dismutase, dendrogram cluster analysis suggested that the interspecific somatic hybrid was similar to A. kolomikta, and might have a higher capacity of cold resistance than A. chinensis. 相似文献
3.
Age, gender and circadian or circasemidian blood pressure and heart rate variation of children. 总被引:1,自引:0,他引:1
Systolic (S) and diastolic (D) blood pressure (BP) and heart rate (HR) of clinically healthy children (24 boys and 15 girls) 3 to 7 years of age were measured with a standard mercury sphygmomanometer at 3-hour intervals for 24 hours in April 1991. The children slept and/or rested from 2100 to 0700 and napped from 1230 to 1530; they had meals at 0730, 1200 and 1800. A statistically significant circadian and about 12-hour (circasemidian) component of variation is documented for SBP and DBP of boys and girls and for HR of boys. No gender difference was found for the circadian and circasemidian components. A positive correlation with age is found for the MESOR and circadian amplitude of SBP and DBP (p < 0.05); a negative correlation with age is found for the MESOR of HR (p < 0.001). 相似文献
4.
Identification and characterization of an {alpha}-mannosidase from Trypanosoma cruzi 总被引:1,自引:0,他引:1
Swanson Paul M.; Carter Clint E.; Hager Cindy; Kim Wan Joon; Obermeier Sarah; Oeltmann Thomas N. 《Glycobiology》1992,2(6):563-569
In this report we describe the first purification and characterizationof the acid -mannosidase from the human parasite Trypanosomacruzi. The purified enzyme exhibited a native mol. wt of 240000 Da and is apparently composed of four identical subunitsof mol. wt 58 000 Da. Each of the four subunits contains oneN-linked high-mannose-type oligosaccharide. The -mannosidaseexhibited a pH optimum of 3.5 and a pI of 5.9. This low pH optimumand the ability of swainsonine to inhibit its activity suggestthat the -mannosidase is a lysosomal enzyme. Antibodies againstthe T.cruzi enzyme did not react with mammalian lysosomal -mannosidaseand, conversely, antibody against a rat lysosomal -mannosidasedid not react with the T.cruzi enzyme. Thus, the T.cruzi enzymeappears to be distinct from its mammalian counterpart. -mannosidase lysosomal enzyme Trypanosoma cruzi 相似文献
5.
Two new loci for hybrid sterility in cultivated rice (Oryza sativa L.) 总被引:17,自引:0,他引:17
J. Wan Y. Yamaguchi H. Kato H. Ikehashi 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,92(2):183-190
Female gamete abortion in Indica-Japonica crosses of rice was earlier identified to be due to an allelic interaction at the S-5 locus on chromosome 6. Recently, in other crosses of rice, similar allelic interactions were found at loci designated as S-7 and S-8, located on chromosomes 7 and 6 respectively. All of them are independent of each other. At the S-5 locus, Indica and Japonica rice have S-5
i
and S-5
j
alleles respectively and Javanicas, such as Ketan Nangka, have a neutral allele S-5
n
.The S-5
i
/S-5
j
genotype is semi-sterile due to partial abortion of female gametes carrying S-5
j
, but both the S-5
n
/S-5
i
and S-5
n
/S-5
j
genotypes are fertile. The S-5
n
allele is thus a wide-compatibility gene (WCG), and parents homozygous for this allele are called wide-compatible varieties (WCV). Such parents when crossed with Indica or Japonica varieties do not show F1 hybrid sterility. Wide-compatible parents have been used to overcome sterility barriers in crosses between Indica and Japonica rice. However, a Javanica variety, Ketan Nangka (WCV), showed typical hybrid sterility when crossed to the Indian varieties N22 and Jaya. Further, Dular, another WCV from India, showed typical hybrid sterility when crossed to an IRRI line, IR2061-628-1-6-4-3(IR2061-628). By genetic analyses using isozyme markers, a new locus causing hybrid sterility in crosses between Ketan Nangka and the Indicas was located near isozyme loci Est-1 and Mal-1 on chromosome 4, and was designated as S-9. Another new locus for hybrid sterility in the crosses between Dular and the IR2061-628 was identified and was found linked to four isozyme loci, Sdh-1, Pox-2, Acp-1 and Acp-2, on chromosome 12. It was designated as S-15. On the basis of allelic interactions causing female-gamete abortion, two alleles were found at S-9, S-9
kn
in Ketan Nangka and S-9
i
in N22 and Jaya. In the heterozygote, S-9
kn
/S-9
i
, which was semisterile, female gametes carrying S-9
kn
were aborted. The hybrid of Dular and IR2061-628, with a genetic constitution of S-15
Du
/S-15
i
, was semi-sterile and the female gametes carrying S-15
Du
were aborted. A Japonica tester variety, Akihikari, and an Indica variety, IR36, were found to have neutral alleles, S-9
nand S-15
n, at these loci, in addition to S-7
nand at S-7. The accumulation of three neutral alleles into a breeding line should help solve the hybrid sterility problem in wide crosses of rice. 相似文献
6.
棉铃虫致病菌BT—931菌株的应用研究 总被引:1,自引:0,他引:1
1992-1993年,作者从菏泽、聊城棉田采集的自然罹病死亡棉铃虫幼虫体内,分离到2个较高毒效的Bt菌株,编号为BT—931和BT—021,经室内毒力测定和田间药效试验表明,防效及保蕾效果接近或超过化学农药,菌药混剂3—5天平均防治效果达87.0-91.6%,增效作用显著。经1994年大田防治示范表明,利用BT—931菌剂。配合化学农药防治棉铃虫,具有成本低、保护天敌、持效期长、增产效益高等优点。本研究对菌剂的田间应用技术进行了试验示范。 相似文献
7.
8.
H. M. Rüffer Liwei Wan A. Lübbert K. Schügerl 《Bioprocess and biosystems engineering》1994,11(4):153-159
Gas-residence time distribution (RTD) response curves measured in a 23 m high pilot plant airlift tower loop reactor, which consisted of a riser, a special downcomer construction and at the top of the riser a large head. The measurements were evaluated by means of a deterministic dispersion model, which yielded the following particular parameters for the riser, downcomer and the head: Gas-Bo numbers, gas-mean residence times, gas holdups, liquid velocities, gas and liquid circulation times as well as a fraction of the large and small bubbles in a model medium (water) and during cultivation of baker's yeast.List of Symbols
A
cross section
-
Bo
Bodenstein number
-
Bo
d
(= l
d
w
G,d
/D
d
)
-
Bo
h
(= l
h
w
G,h
/D
h
)
-
Bo
r
(= l
r
w
G,r
/D
r
)
-
D
longitudinal dispersion coefficient
-
E
gas holdup
-
E(t)
RTD-density function
-
L, l
length parameter
-
q
fraction of the gas throughput which is not recirculated (approximately equal to fraction of the large bubbles)
-
r
fraction of the throughput which is recirculated (approximately equal to the fraction of the small bubbles)
-
t
c
circulation time
-
t
cL
liquid circulation time
-
t
c,L
*
liquid circulation time calculated from the measured w
Ld
in the downcomer
-
V
h
hydrodynamical calculated gas-liquid volume
-
V
d
h
(=V
d+0.75/2 V
k
)
-
V
k
h
=(0.25V
k
)
-
V
r
h
= (V
r+0.75/2 V
k
)
-
V
L
liquid volume
-
V
G
dispersed gas volume
-
V
G
*
gas throughput at the gas distributor (given in m3/h) under standard conditions, 1 bar and 25°C)
-
V
G,d
*
gas throughput in downcomer (=V
G
*
)
-
V
G,h
*
gas throughput in head (=V
G
*
)
-
V
G,r
*
gas throughput in riser (V
G
*
(1+)
-
w
g
gas velocity
-
w
G,rel
relative gas velocity with respect to the liquid velocity w
L
-
w
G,d
gas velocity in the downcomer (=w
G,rel
–w
Ld
)
-
w
G,h
gas velocity in the head (=w
G,rel
) (since wLh = o)
-
w
G,r
gas velocity in the riser (=w
G,rel
+w
Lr
)
-
w
L
liquid velocity
-
w
L,d
liquid velocity in the downcomer measured with mass flow meter
-
w
sg
·w
SL
superficial gas and liquid velocities
-
first moment of the response curve
-
mean residence time
Indices
d
downcomer
-
G
gas phase
-
h
head
-
L
liquid phase
-
r
riser
-
h
hydrodynamic (upper position)
Dedicated to the 65th birthday of Proffessor Fritz Wagner.The authors gratefully acknowledge the financial support by the Krupp Industrietechnik, Grevenbroich and the support of Pleser Co, Darmstadt. H. M. Rüffer thanks the Verband der Chemischen Industrie for a Fond der Chemie scholarship, and W. Liwei thanks the government of Lower Saxony for a graduate scholarship. 相似文献
9.
D. P. Chora L. Reddy S. K. Gupta L. Wan P. A. Mathieu R. L. Shoemaker J. S. Rhim 《In vitro cellular & developmental biology. Animal》1994,30(8):539-546
Summary Cystic fibrosis (CF) involves abnormalities in mucus production and secretion of the airway. Studies of the regulation of
airway mucin production and secretion has been difficult due to the lack of in vitro models of the airway epithelial cells
which express functional differentiation. Because the majority of the mucin in the airway is apparently produced by the submucosal
glands, we have focused our attention on the development of cell culture models of human airway submucosal glands. This report
describes the propagation of CF airway submucosal gland epithelial cells which continue to express mucin production. The CF
bronchus was obtained from a 31-yr-old patient who received a double lung transplant. The glands were dissected out and primary
cultures prepared by the explant/outgrowth procedure. The cells were immortalized by infection with Adl2-SV40 hybrid virus.
The cultures are maintained in serum-free keratinocyte basal medium supplemented with insulin (5μg/ml), hydrocortisone (0.5μg/ml), epidermal growth factor (10 ng/ml), bovine pituitary extract (25μg/ml), and antibiotics. Cultures were passaged using 0.125% trypsin in Ca+2 and Mg+2-free Hanks’, balanced salt solution. Polymerase chain reaction (PCR) analysis demonstrated that the cells were homozygous
for the ΔF508 mutation. Morphologic observations showed that the cells were epithelial and were interconnected by sparsely
distributed desmosomes. Their cytoplasm contained secretory-type structures including abundant Golgi, rough endoplasmic reticulum,
and secretory vesicles. Immunofluorescent studies determined that all cells were positive for cytokeratins, mucin glycoconjugates,
and cystic fibrosis transmembrane conductance regulator. The cultures secreted substantial amounts of mucin glycoproteins
and expressed the MUC-2 mucin gene. Patch clamp experiments revealed that the cells expressed defective Cl− channels which were not activated by Forskolin. 相似文献
10.